KEF LS50 amp review (Cyrus One, Rega Elex-R, Naim Nait 5si)

chasingdopamine

Standard Member
20190101_013336.jpg
20181228_220223.jpg


Hey everyone,

EDIT: This review is getting quite long now as I've added to it with every upgrade in chronological order. Initially I start with the LS50s driven by the Cyrus One, before comparing the Rega Elex-R and Naim Nait 5si in depth. At the bottom you will find my review of the LS50W actives which is where my upgrade path led me and what I currently own.





I've bought the LS50s a few months ago and absolutely loving them. They are an amazing pair of speakers for the price.

i just wanted to note some observations and impressions regarding amp choices (~£700-£1500) after many demos. I was a bit overwhelmed with options at first so hopefully this will help inform someone else's choice.

For reference in my demos my chain was KEF LS50 < *AMP* < Chord 2Qute DAC < Tidal Hifi. At home i use Atacama Moseco 6 stands filled all the way with atabites ontop of granite slabs in a small/medium sized room.

Initial choice:

- Cyrus One (£699) -
This is the amplifier i initially brought with my LS50s at a decent discount as part of my LS50 Package. I got the standard version without digital inputs (which retails at £999)
The extensive list of features was nice to have, even though i didn't use a lot of them. The headphone output works well enough, but is unremarkable. The phone remote control app was really useful though, and a good thing too because the remote is terrible.

At 100Wpc class D they drove the LS50s comfortably and with authority. The bass response was very powerful with a decent amount of tightness and texture. The amp was an excellent all rounder for its price. I felt it did everything quite well (compared to others of its price). lacking and excelling at nothing in particular, it just got on with it and made everything sound decent. it could pretty much handle every genre of music reasonably well, and also sounded good with regular TV viewing.
The sound signature was very lively and entertaining. It captures attention immediately has a high level of engagement and enthusiasm. Over time i actually found that the sound was a bit too forward, and always demanding for attention. This was particularly true for voices. Although this prominence is at first appealing for vocal or acoustic music, after a while it got a bit fatiguing.
The tonality seemed overall well balanced, neither too bright or warm with a decent but no excessive amount of air and sparkle. The soundstage was big enough compared to similarly priced amps but nothing astonishing. Detail and rhythm were i felt a bit lacking. I felt there were likely entire layers of the music missing from the the presentation and the timing was offset.

This reason combined with the fact that the input signal was occasional clipped (the Cyrus One has a max input of 2.5V RMS while my DAC outputs at an unusually high 3V RMS) i decided to sell the amp and upgrade it. I still think that its a very good all rounder and i would still recommend it for the LS50s.

So having decided to now upgrade my Cyrus One, i was looking for amps in the price range of £700-1500. I wont review them all, but have listed them below. After many in-store demos I eventually narrowed it down to two, but the runners up were:
(Ranking is very approximate as i could not A/B all of them against east other)

1. Roksan K3 (£1300)
2. Quad VA One (£1299)
3. Musical Fidelity M3si (£1099)
4. YBA Heritage A100 (£1500)
5. Yamaha A-S1100 Amplifier (£1099)
6. Cambridge CXA80 (£799)
7. Marantz PM8006 (£1099)
8. Arcam SA20 (£999)

Eventually my choice was narrowed down to two amps, and this is where the competition got really heated.

I went to 3 different demos, spending approximately 5 hours total A/Bing these two against each other. It was a very very close call, and i would have been happy with either. I dont think you can make a wrong choice here. I will post my impressions of both together in direct comparison.

- Rega Elex-R (£949) vs Naim Nait 5si (£1099)-

First up was the Rega Elex-R.
The Elex was a fantastic match with the LS50s. It was head and shoulders above the Cyrus in every way. The Rega drove them very well and had plenty of power. The Elex comes out of the gate hard, an incredibly engaging sound and presentation. The bass response was great. Powerful, deep, textured and tight. The detail, separation and air was the best i had heard. The timing and rhythm was sensational and again the best 've heard at this price. Vocals were sweet and engaging with great intimacy. The Elex was textured throghout the entire frequency spectrum and had a remarkable sense of cohesion. Everything was woven together so well on its soundstage. And speaking of soundstage, the Elex projected a massive 3D soundstage which was considerably wider deeper and longer than its competition. The separation of musical information and layers on this stage was very very impressive. The amp just had such a sense of graceful energy about it, and was at all times incredibly refined and elegant. This held true at all volumes, from very low level background listening to hearing damage thresholds, the Elex held onto its personality.

Sounds like an absolute no brainier - i was reaching for my wallet already. i thought i might as well listen to a few more songs and give the Naim Nait 5si a chance too. As i listened for longer on the Elex i fell deeper in love with the sound, however i couldn't take my mind off one thing. This is where i ran into a problem. The amp was bright, and i do not tolerate brightness well. The KEFs are very transparent and will expose whatever they are paired with. My DAC (Chord 2qute) produces a fantastic sound, but can be a bit bright at times. There was so much air and detail, but there was this contant leanness and metallic glare which was present at all times. the sound was so sweet but felt thin. On certain notes the elex felt almost piercing, and after a certain time it felt edgy. Indeed the "edges" of every detail felt sharp, and there was so much detail that when observing the whole rather than listening to the parts there was a lot of edge present in the mix. This was not an issue with all tracks, but it was very real on others. I felt that if my DAC less bright it would have been perfect. This downside was only price to pay for an otherwise absolutely sensational <£1000 amp.

Next up was the Naim Nait 5si. Boy did it have its work cut out for it following the Elex, line up the same songs.

Straight out the gate. There was an instant relief from the brightness, leanness, edginess and metallic quality of the Elex. i cannot understate the extent of this relief. It was like walking into the chilled section of a supermarket on a scorching summers day. There was darkness and blackness to the soundcape and i felt as if i was running my hand under a cold tap after touching a stove. The sound was fuller, deeper and darker. emotional expression was much better and nothing short of incredible. Voices felt more realistic and true to life. I felt closer to the music and its message. indeed it felt not as if i was diving deeply into the emotional essence of the music, but instead it was pulling me into it. With acoustic female vocals there was a deep sense of emotional gravity. For all of its elegence and refinement, the Elex just could not match the raw emotional transparancy of the Naim. It felt as if the Elex put into sharp focus the technical wizardry of the DAC, whereas the Naim dived deeply into the emotional core of the information. it really did something special.

Of course this is life so it had to come at a cost. Firstly, at 60Wpc the Naim did feel underpowered compared to the Elex. The bass was considerably weaker, and was less textured with less control and tightness. Volume control was also not as consistent, with the elex holding its ground better at lower and higher volumes. Although the Naim wasn't as bright, it did had intermittent harshness. This would peak up every now and again, but was absent for alot of the time unlike the Elex's glare.

By far the biggest difference was in the presentation of the musical soundscape. The Elex had a wider, taller and deeper sound stage. Musical information had greater seperation, and felt evenly spaced and finely woven together through a large stage. In contrast, the Naim had a much smaller soundstage and musical information seemed compacted together. However its worth noting that the detail wasn't gone, it just wasn't spread out over a large space with its edges and grain cut into the vast blackness like the Elex. Instead the detail was woven closer into a smaller and more cohesive whole. Still very detailed and resolving, but the edges of the music were softer and more forgiving. The Elex seems much more detailed as first as it made a big song and dance about its information. The Naim in contrast was more reserved, not showing off by trading substance for flash. On first listen there was no doubt the Elex was better with technicalities. it wasn't even close, a landslide victory.

So it was a trade off. Switching from the Elex to the Naim gave a sense that immediately space and scale was gone, information was gone or harder to notice, and power and drive was reduced. The amp felt weaker. However there was also a sense of massive relief from the glare and edge. it also felt like music was significantly more emotionally prominent and relaxing. Once again you were listening with your heart and soul instead of your mind. It seemed as if Naim had created an amplifier with the sole objective of emotional accuracy and transparancy, and everything else was an afterthought. It was less cognitively engaging, but your attention and mindspace could drift more into the emotional from the auditory.

i will attempt to describe the vast difference in the two presentations with a visual metaphor. This imagery seemed to sum up my A/B for Lana Del Rey's songs "Changes" and "love" .The sound of the Elex felt like staring at an elegant and graceful tapestry woven with striking detail and resolution of the music. The Naim felt like being pulled into flowing cloud of emotions.

Switching back to the Elex from the Naim, and instantly the sound expanded, separating and filling out the space. There was more power, air and sparkle. it felt as if layers of information had been released and could now breath freely again. You snap into analytical processing and decide that "this is the better sound, no contest". During the song, your attention has drifted to that glare again and again. Its edgy but you finally manage to relax, and now the amp is not bright at all but instead fantastically musical. But then the cymbals crash and the edge is back. The amp demanded my attention. With the Naim i felt, but now with the Elex i think.

It must be noted that the tonality and presentation of the two amps are so different, that switching between them really highlights the sharp contrasts noted above. They are both incredibly musical, and although the Naim was better with emotional vocal music they both handled emotional expression exceptionally well. They also both were very good in regards to dynamics and transients. Overall the Elex is "better", but the question was is it more enjoyable in the long run? It all boiled down to a single question: would the brightness and edge of the Elex be fatiguing?

The Verdict

I changed my mind a dozen times until the very last moment. i changed it again and again. it was such a close call as they were so different, yet both so good. it felt as if i couldn't make a wrong choice, and yet somehow i couldn't make a right one either. A home demo would have settled it for sure, but i did not have that option.

In the end, i went with the Naim Nait 5si. For all it couldn't do that the Elex could, it did emotions and it did them exceptionally. and that's what music is about at the end of the day. I wanted to feel the music, not think about the sound.


Update (4 weeks):

I've now had about a month on the Naim to listen and reflect upon my choice. I don't regret it one bit, and I believe I would make the same choice again. I have grown to love is sound signature and it's place within my system. It's a pleasure listening daily, and fair credit to the Kef LS50s and Chord 2Qute in this regard too. They synergise well with the Naim Nait 5si and I would recommend anyone to give them a demo of they are within your price range.

Update (3 months):

So I had hoped I would stick with the setup for longer, but upgradeitis hit me hard and I couldn't resist. Although the naim was nothing short of amazing at what it did, over time it felt a bit too bright, fatiguing and weak in bass. Certain genres felt lacking and I found it was restricting my musical taste. I ran a 6+ dB bass boost for a while, but it still wasn't cutting it. The Rega had better bass for sure, but even that wasn't really where I wanted bass wise and I remember it being even brighter.

After a few demos I traded the lot in for the KEF LS50W. It really is what everyone says it is and more. It is what the LS50s were born to be. After trying so many amps, none could even come close. Some of those above amps undoubtedly have better materials or build quality, but Kef have created an amp specifically matched for the LS50 driver which is superior by design. It's designed to drive one load and one load only, and is not an easy one to drive as all my different amp demos have taught me.The actives are bi-amped, active crossover, 230wpc with DSP.

How was the sound? Absolutely phenomenal. Beyond breathtaking, and it moved me to my core. Compared to the passives driven by the Naim Nait 5si, Rega Elex-R and Cyrus One (the amps I've didn't most time with), it just blows them all away without breaking a sweat. It's not even close, a landslide victory. The LS50W was far more transparent, more dynamic, more true to the sound. The clarity was incredible. The soundstage was bigger too. Imaging was much better and genuinely holographic. I did a side by side demo and the LS50W makes the passives sound downright flat and 2D. Switch back to the LS50W and it's like you've activated the 3D switch. By far and away the biggest improvent is the bass. The bass is so much better. It's much deeper, hitting a solid 40hz (compared with the 70 I was measuring on the passives + Naim). It's more textured, detailed and rythmic. Incredible for such a small driver. It was shocking to hear how much musical information and impact I had been missing with the passives. The midrange is clear and more transparant, and the highs are just as brilliant. Overall the ls50W was more revealing, less bright, with better tonality across the entire spectrum. It felt like the LS50s just got the perfect amp pgrade. After so many combinations it finally felt like it all clicked into place.

The built in streamer works well with tidal and Spotify connect. The DSP is easy to use and is a great ear to adjust the sound to your taste. Im currently using it in stand mode set to free space, running 6+ dB bass boost with 'extra' bass extension. I vary the treble trim from -1.5db to 0 dB bass on my mood and song choice.

I can't recommend the LS50W enough. They are my endgame for a long timetim I know it's need to spend so much more to get any incremental upgrades. The only thing I will add at some point is a sub. I tried them with a REL 7ti and they were fantastic. Really gets that last octave out there. I've also added some GIK acoustic panels and I couldn't be happier with the sound.

The LS50W is by far the best value of any ls50 combination I've heard to date. You just won't bear it for the price. You would need to spend so much money to even come close with the passives. If you are considering the LS50, try and book a demo to hear the wireless before you get the passives. If you have the passives and you like what you hear then you could consider a trade in or sell the seperates to get the wireless. This is just my impression, but I would encourage you to hear for yourself.

So it finally feels like my upgrade journey with the KEF is over. I don't regret that I bounced around with so many amps as I enjoy the journey. In the egg me though I'm happy to have arrived at the destination i wanted. If I ever move on from the LS50s it would most certainly be to a different speaker entirely. A fantastic speaker from KEF, and an even better sequel to the original
 
Last edited:

Ugg10

Distinguished Member
Great write up, thanks. I was about to suggest you could add a second hand NAP200 which may keep the Naim PRaT but add a bit more control and beef to the bass but it does not seem to have a pre-out so that is not an option.

Anyway, enjoy.
 

Apollo83

Active Member
Great review.
I also demoed the Elex and the SA20s and PM8006.
I could not believe how much better the Elex was.
In the end I went for the Rega Brio, a remarkably similar performer to its big brother at the volumes I listen to and only losing out as I drove the volume higher.
This pairs really nicely with the analogue record player sound (great phono amp) and the Rega Apollo CD player.

But from your description it sounds like your Nait is the perfect partner for the slightly bright 2qute.

Enjoy!
 

gibbsy

Moderator
What a great write up and virtually sums up how I felt in my audition between a Rega Elicit R and the Naim Nait XS2. Like you they were to be hooked up to KEF speakers, in my case the R300s and the DAC on my own Marantz SACD player.

I had almost convinced myself the audition was a mere confirmation of what I wanted, which was the Naim. I played the Naim first using Ran 'n Bone Man's Human CD, just like you I found a very musical interpretation. The second CD was to check out female vocals in the shape of Laura Marling's I speak because I can, again the Naim performed admirably. One of the main points of the Naim was the full size headphone port.

AudioT had also set up the Rega Elicit R and the 5si. The next to go was the Rega and in went Rag 'n Bone Man. Wow. The hair of my arms stood up once the bass kicked in, so much different from the Naim, quicker, sharper and as you said the whole of the soundstage was opened up. Where I differ from you is that I didn't find the sound fatiguing. With Marling's voice the Rega and Naim performance was almost identical, maybe the Naim had the edge here being slightly more musical but again the instruments soared with the Rega.

Only one way to check was to play Holst's The Planets. Here again the Rega's soundstage was huge, instruments were given plenty of room to breath and all aspects of the orchestra could be placed both in depth and width. Putting the Naim back on I played Mars and Jupiter but it was evident that the Rega had a definite edge on orchestral works.

Now the doubt set in. The Rega doesn't have a headphone port and I would have to rely on the headphone amp built into the Marantz player, which was pretty adequate, especially with my Shure 1540s. So I came out with an amp that I really didn't have any intention of buying but was just in the audition for comparison. I should have auditioned the Marantz 8006 but AudioT couldn't get one in time. I had to limit my options because of the lack of depth in my cabinet so some of other amps you've mentioned were out because of their depth.

Since buying the Rega I've also bought a pair of Oppo PM1 headphones and knew there was something missing with just using the Marantz' headphone port. Do I regret going for the Rega, I wondered if the Naim would have done a good job with these beautiful headphones. Now I've had to buy a pure headphone amp in the shape of a Lehmann Linear and the Oppos are soaring.

It just goes to show how important auditions are as we are all different and when it comes down to it our own ears are the best reviewers of any equipment. Well done for a very interesting and in depth review.
 

chasingdopamine

Standard Member
What a great write up and virtually sums up how I felt in my audition between a Rega Elicit R and the Naim Nait XS2. Like you they were to be hooked up to KEF speakers, in my case the R300s and the DAC on my own Marantz SACD player.

I had almost convinced myself the audition was a mere confirmation of what I wanted, which was the Naim. I played the Naim first using Ran 'n Bone Man's Human CD, just like you I found a very musical interpretation. The second CD was to check out female vocals in the shape of Laura Marling's I speak because I can, again the Naim performed admirably. One of the main points of the Naim was the full size headphone port.

AudioT had also set up the Rega Elicit R and the 5si. The next to go was the Rega and in went Rag 'n Bone Man. Wow. The hair of my arms stood up once the bass kicked in, so much different from the Naim, quicker, sharper and as you said the whole of the soundstage was opened up. Where I differ from you is that I didn't find the sound fatiguing. With Marling's voice the Rega and Naim performance was almost identical, maybe the Naim had the edge here being slightly more musical but again the instruments soared with the Rega.

Only one way to check was to play Holst's The Planets. Here again the Rega's soundstage was huge, instruments were given plenty of room to breath and all aspects of the orchestra could be placed both in depth and width. Putting the Naim back on I played Mars and Jupiter but it was evident that the Rega had a definite edge on orchestral works.

Now the doubt set in. The Rega doesn't have a headphone port and I would have to rely on the headphone amp built into the Marantz player, which was pretty adequate, especially with my Shure 1540s. So I came out with an amp that I really didn't have any intention of buying but was just in the audition for comparison. I should have auditioned the Marantz 8006 but AudioT couldn't get one in time. I had to limit my options because of the lack of depth in my cabinet so some of other amps you've mentioned were out because of their depth.

Since buying the Rega I've also bought a pair of Oppo PM1 headphones and knew there was something missing with just using the Marantz' headphone port. Do I regret going for the Rega, I wondered if the Naim would have done a good job with these beautiful headphones. Now I've had to buy a pure headphone amp in the shape of a Lehmann Linear and the Oppos are soaring.

It just goes to show how important auditions are as we are all different and when it comes down to it our own ears are the best reviewers of any equipment. Well done for a very interesting and in depth review.

Interesting to read your observations. Indeed people have different physiological and psychological tolerances and sensitivities across the audio spectrum. System synergy is also huge. I would never advise anyone to buy a four figure product without a couple demos and shootouts.

I did not give the Elicit-R a proper listen as it was outside my price range for now. If the Elex is anything to go by i have no doubt its brilliant. I demoed the Marantz 8006 and in my opinion you didn't miss out on anything spectacular. It wasn't a terrible amp, but it was very unremarkable. i felt for the price i could beat if i just pulled them out of a hat.

I can confirm however that the Naim Nait 5si has a decent enough headphone output, but i would recommend a dedicated headphone amp all the way if you listen via headphones often. You just cant beat dedicated hardware unless the price difference gets ridiculous. I also have Shure 1540s and found that they are absolutely brilliant with a Chord Mojo. The PM1s i've heard and they are very good. The headphone game is massive and depending on where you live its actually much easier to demo gear as you can demo multiple in a single session.
 

gibbsy

Moderator
I found that where I live getting dedicated headphone amp auditions was a nightmare. Almost all carried the Rega Ear but I had already been put of that by reports of floor noise with 32 ohm high sensitivity headphones which would certainly have impacted both the Shure 1540s and the Oppos. I did do a lot of research into the Lehmann and even contacted them direct. Thankfully my local AudioT managed to get a well run demo and I was able to get a good demo with it. Impressive.

I was guilty about going against all the advice I give on here about auditions being essential and ordered the Oppos blind though. The other two pair of headphones were auditioned at Richer Sounds, who, in fairness do seem to carry a large selection to try.
 

chasingdopamine

Standard Member
I'm not sure where you live but if you ever find yourself in London I can definitely recommend audio sanctuary and spiritland headphone bar. Between them they carry an outrageous selection of headphones/amps and were very acommodating with long drop by demos.
 

gibbsy

Moderator
London! Too far for me. Don't like big cities. Worked there for six weeks back in the 1970s that was enough. Thanks for the info but I'm more than happy now with the Oppos and the Lehmann Linear. Dare not raid the hifi coffers for a good while now.:)
 
Very interested and appreciate the review.
I have a Cyrus with slave amp (Smart power) with Psxr power and wonder if I will hear improved sound stage etc.

Had a first pass at local HiFi shop listening to Creek Dynaudio/B&W and Rega Elex R with same speakers. A rushed demo (car parking issues) but initial impression was Creek Dyn combo were harsh. Rega B&W nearer to my musical taste.
I have always been looking for a solid bass, clear mid and top end that did not cause fatigue.
Had issues at first with the Cyrus being a bit bright until after many forum searches used Van Damien blue speaker cable.
 

ash b

Novice Member
Hey chasingdopamine

This was an extremely valuable review. Thank you for taking the time to post and update it.

I am wondering whether you considered the active speakers ls50 and what your thoughts are on its sound signature vs the naim or the rega combo.

Also what were your thoughts on the arcam sa20 as they are the easiest to demo in London.

I’m also curious about the Dali rubicon 2 if anyone has anything to add about it.


In the end, i went with the Naim Nait 5si. For all it couldn't do that the Elex could, it did emotions and it did them exceptionally. and that's what music is about at the end of the day. I wanted to feel the music, not think about the sound.


Update (4 weeks):

I've now had about a month on the Naim to listen and reflect upon my choice. I don't regret it one bit, and I believe I would make the same choice again. I have grown to love is sound signature and it's place within my system. It's a pleasure listening daily, and fair credit to the Kef LS50s and Chord 2Qute in this regard too. They synergise well with the Naim Nait 5si and I would recommend anyone to give them a demo of they are within your price range.
 

chasingdopamine

Standard Member
Hey chasingdopamine

This was an extremely valuable review. Thank you for taking the time to post and update it.

I am wondering whether you considered the active speakers ls50 and what your thoughts are on its sound signature vs the naim or the rega combo.

Also what were your thoughts on the arcam sa20 as they are the easiest to demo in London.

I’m also curious about the Dali rubicon 2 if anyone has anything to add about it.

Regarding the Arcam sa20, i did not like it at all. dont get me wrong its not a terrible amp, but for the asking price of £999 you can do alot better. Cambridge CXA60/80 was noticably better, as well as Rega Brio/Elex.

Regarding the LS50W Actives, i have recently had a few demos.
They are everything people say about them and certainly live up to the hype. they are head and shoulders above the LS50 passives with any amp i've tried, and i've head them with several £3000+ amps. Its not even close really. The amps may not use as high quality components as £1000 separates amps, but the LS50W amps are superior by design as they are perfectly matched to the driver. The LS50s are really hard to match with amps, so its not surprising an amp specifically designed for it sounds so good. The bass is so much better, stronger and deeper. The soundstage is significantly wider. transparency is slightly better, and the overall tonal balance is much much better. The DSP, active crossover and dual matched amplifiers really takes them over the top. you would need to spend stupid money to even have a chance of getting equal performance with the passives. The only time it may not make sense is if you use an analogue source (analogue input is converted to digital then back to analouge).

So i will upgrade to the LS50W, but i haven't done so yet. Selling my passives, Naim Nait5si and Chord2Qute dac will incur a large loss as they are so new yet not brand new (about £1000 in 2-3 months of usage). I will probably keep with the separates until i get a decent price or enough time has passed for me to justify the depreciation, then get the LS50W.

If you can afford it, get the LS50W. Superfi and Peter Tyson do 5 year warranties in the UK. If i could go back to when i was trying to match amps to my passives by chucking around four figures, i would have pounced on the actives.

i would advise you not to take my or anyone elses word for it. Try and organise a demo, hearing is believing.
 

Southern soul

Active Member
although the ls50 wireless are good they do have many floors (app being a major floor), and can easily be bettered by separates, i have tried and demo's many many different amplifiers at different price points up to £5k and my current system is smoother with a wider soundstage, more transparent with better clarity and increased bass response. yes it's more expensive but i prefer to mould the sound to my liking.
 

chasingdopamine

Standard Member
I've just updated the main post with my impressions for the KEF LS50W. I've had them for a couple weeks now and they blow me away every time!
 

KyleM

Active Member
View attachment 1106884 View attachment 1101575

Hey everyone,

EDIT: This review is getting quite long now as I've added to it with every upgrade in chronological order. Initially I start with the LS50s driven by the Cyrus One, before comparing the Rega Elex-R and Naim Nait 5si in depth. At the bottom you will find my review of the LS50W actives which is where my upgrade path led me and what I currently own.





I've bought the LS50s a few months ago and absolutely loving them. They are an amazing pair of speakers for the price.

i just wanted to note some observations and impressions regarding amp choices (~£700-£1500) after many demos. I was a bit overwhelmed with options at first so hopefully this will help inform someone else's choice.

For reference in my demos my chain was KEF LS50 < *AMP* < Chord 2Qute DAC < Tidal Hifi. At home i use Atacama Moseco 6 stands filled all the way with atabites ontop of granite slabs in a small/medium sized room.

Initial choice:

- Cyrus One (£699) -
This is the amplifier i initially brought with my LS50s at a decent discount as part of my LS50 Package. I got the standard version without digital inputs (which retails at £999)
The extensive list of features was nice to have, even though i didn't use a lot of them. The headphone output works well enough, but is unremarkable. The phone remote control app was really useful though, and a good thing too because the remote is terrible.

At 100Wpc class D they drove the LS50s comfortably and with authority. The bass response was very powerful with a decent amount of tightness and texture. The amp was an excellent all rounder for its price. I felt it did everything quite well (compared to others of its price). lacking and excelling at nothing in particular, it just got on with it and made everything sound decent. it could pretty much handle every genre of music reasonably well, and also sounded good with regular TV viewing.
The sound signature was very lively and entertaining. It captures attention immediately has a high level of engagement and enthusiasm. Over time i actually found that the sound was a bit too forward, and always demanding for attention. This was particularly true for voices. Although this prominence is at first appealing for vocal or acoustic music, after a while it got a bit fatiguing.
The tonality seemed overall well balanced, neither too bright or warm with a decent but no excessive amount of air and sparkle. The soundstage was big enough compared to similarly priced amps but nothing astonishing. Detail and rhythm were i felt a bit lacking. I felt there were likely entire layers of the music missing from the the presentation and the timing was offset.

This reason combined with the fact that the input signal was occasional clipped (the Cyrus One has a max input of 2.5V RMS while my DAC outputs at an unusually high 3V RMS) i decided to sell the amp and upgrade it. I still think that its a very good all rounder and i would still recommend it for the LS50s.

So having decided to now upgrade my Cyrus One, i was looking for amps in the price range of £700-1500. I wont review them all, but have listed them below. After many in-store demos I eventually narrowed it down to two, but the runners up were:
(Ranking is very approximate as i could not A/B all of them against east other)

1. Roksan K3 (£1300)
2. Quad VA One (£1299)
3. Musical Fidelity M3si (£1099)
4. YBA Heritage A100 (£1500)
5. Yamaha A-S1100 Amplifier (£1099)
6. Cambridge CXA80 (£799)
7. Marantz PM8006 (£1099)
8. Arcam SA20 (£999)

Eventually my choice was narrowed down to two amps, and this is where the competition got really heated.

I went to 3 different demos, spending approximately 5 hours total A/Bing these two against each other. It was a very very close call, and i would have been happy with either. I dont think you can make a wrong choice here. I will post my impressions of both together in direct comparison.

- Rega Elex-R (£949) vs Naim Nait 5si (£1099)-

First up was the Rega Elex-R.
The Elex was a fantastic match with the LS50s. It was head and shoulders above the Cyrus in every way. The Rega drove them very well and had plenty of power. The Elex comes out of the gate hard, an incredibly engaging sound and presentation. The bass response was great. Powerful, deep, textured and tight. The detail, separation and air was the best i had heard. The timing and rhythm was sensational and again the best 've heard at this price. Vocals were sweet and engaging with great intimacy. The Elex was textured throghout the entire frequency spectrum and had a remarkable sense of cohesion. Everything was woven together so well on its soundstage. And speaking of soundstage, the Elex projected a massive 3D soundstage which was considerably wider deeper and longer than its competition. The separation of musical information and layers on this stage was very very impressive. The amp just had such a sense of graceful energy about it, and was at all times incredibly refined and elegant. This held true at all volumes, from very low level background listening to hearing damage thresholds, the Elex held onto its personality.

Sounds like an absolute no brainier - i was reaching for my wallet already. i thought i might as well listen to a few more songs and give the Naim Nait 5si a chance too. As i listened for longer on the Elex i fell deeper in love with the sound, however i couldn't take my mind off one thing. This is where i ran into a problem. The amp was bright, and i do not tolerate brightness well. The KEFs are very transparent and will expose whatever they are paired with. My DAC (Chord 2qute) produces a fantastic sound, but can be a bit bright at times. There was so much air and detail, but there was this contant leanness and metallic glare which was present at all times. the sound was so sweet but felt thin. On certain notes the elex felt almost piercing, and after a certain time it felt edgy. Indeed the "edges" of every detail felt sharp, and there was so much detail that when observing the whole rather than listening to the parts there was a lot of edge present in the mix. This was not an issue with all tracks, but it was very real on others. I felt that if my DAC less bright it would have been perfect. This downside was only price to pay for an otherwise absolutely sensational <£1000 amp.

Next up was the Naim Nait 5si. Boy did it have its work cut out for it following the Elex, line up the same songs.

Straight out the gate. There was an instant relief from the brightness, leanness, edginess and metallic quality of the Elex. i cannot understate the extent of this relief. It was like walking into the chilled section of a supermarket on a scorching summers day. There was darkness and blackness to the soundcape and i felt as if i was running my hand under a cold tap after touching a stove. The sound was fuller, deeper and darker. emotional expression was much better and nothing short of incredible. Voices felt more realistic and true to life. I felt closer to the music and its message. indeed it felt not as if i was diving deeply into the emotional essence of the music, but instead it was pulling me into it. With acoustic female vocals there was a deep sense of emotional gravity. For all of its elegence and refinement, the Elex just could not match the raw emotional transparancy of the Naim. It felt as if the Elex put into sharp focus the technical wizardry of the DAC, whereas the Naim dived deeply into the emotional core of the information. it really did something special.

Of course this is life so it had to come at a cost. Firstly, at 60Wpc the Naim did feel underpowered compared to the Elex. The bass was considerably weaker, and was less textured with less control and tightness. Volume control was also not as consistent, with the elex holding its ground better at lower and higher volumes. Although the Naim wasn't as bright, it did had intermittent harshness. This would peak up every now and again, but was absent for alot of the time unlike the Elex's glare.

By far the biggest difference was in the presentation of the musical soundscape. The Elex had a wider, taller and deeper sound stage. Musical information had greater seperation, and felt evenly spaced and finely woven together through a large stage. In contrast, the Naim had a much smaller soundstage and musical information seemed compacted together. However its worth noting that the detail wasn't gone, it just wasn't spread out over a large space with its edges and grain cut into the vast blackness like the Elex. Instead the detail was woven closer into a smaller and more cohesive whole. Still very detailed and resolving, but the edges of the music were softer and more forgiving. The Elex seems much more detailed as first as it made a big song and dance about its information. The Naim in contrast was more reserved, not showing off by trading substance for flash. On first listen there was no doubt the Elex was better with technicalities. it wasn't even close, a landslide victory.

So it was a trade off. Switching from the Elex to the Naim gave a sense that immediately space and scale was gone, information was gone or harder to notice, and power and drive was reduced. The amp felt weaker. However there was also a sense of massive relief from the glare and edge. it also felt like music was significantly more emotionally prominent and relaxing. Once again you were listening with your heart and soul instead of your mind. It seemed as if Naim had created an amplifier with the sole objective of emotional accuracy and transparancy, and everything else was an afterthought. It was less cognitively engaging, but your attention and mindspace could drift more into the emotional from the auditory.

i will attempt to describe the vast difference in the two presentations with a visual metaphor. This imagery seemed to sum up my A/B for Lana Del Rey's songs "Changes" and "love" .The sound of the Elex felt like staring at an elegant and graceful tapestry woven with striking detail and resolution of the music. The Naim felt like being pulled into flowing cloud of emotions.

Switching back to the Elex from the Naim, and instantly the sound expanded, separating and filling out the space. There was more power, air and sparkle. it felt as if layers of information had been released and could now breath freely again. You snap into analytical processing and decide that "this is the better sound, no contest". During the song, your attention has drifted to that glare again and again. Its edgy but you finally manage to relax, and now the amp is not bright at all but instead fantastically musical. But then the cymbals crash and the edge is back. The amp demanded my attention. With the Naim i felt, but now with the Elex i think.

It must be noted that the tonality and presentation of the two amps are so different, that switching between them really highlights the sharp contrasts noted above. They are both incredibly musical, and although the Naim was better with emotional vocal music they both handled emotional expression exceptionally well. They also both were very good in regards to dynamics and transients. Overall the Elex is "better", but the question was is it more enjoyable in the long run? It all boiled down to a single question: would the brightness and edge of the Elex be fatiguing?

The Verdict

I changed my mind a dozen times until the very last moment. i changed it again and again. it was such a close call as they were so different, yet both so good. it felt as if i couldn't make a wrong choice, and yet somehow i couldn't make a right one either. A home demo would have settled it for sure, but i did not have that option.

In the end, i went with the Naim Nait 5si. For all it couldn't do that the Elex could, it did emotions and it did them exceptionally. and that's what music is about at the end of the day. I wanted to feel the music, not think about the sound.


Update (4 weeks):

I've now had about a month on the Naim to listen and reflect upon my choice. I don't regret it one bit, and I believe I would make the same choice again. I have grown to love is sound signature and it's place within my system. It's a pleasure listening daily, and fair credit to the Kef LS50s and Chord 2Qute in this regard too. They synergise well with the Naim Nait 5si and I would recommend anyone to give them a demo of they are within your price range.

Update (3 months):

So I had hoped I would stick with the setup for longer, but upgradeitis hit me hard and I couldn't resist. Although the naim was nothing short of amazing at what it did, over time it felt a bit too bright, fatiguing and weak in bass. Certain genres felt lacking and I found it was restricting my musical taste. I ran a 6+ dB bass boost for a while, but it still wasn't cutting it. The Rega had better bass for sure, but even that wasn't really where I wanted bass wise and I remember it being even brighter.

After a few demos I traded the lot in for the KEF LS50W. It really is what everyone says it is and more. It is what the LS50s were born to be. After trying so many amps, none could even come close. Some of those above amps undoubtedly have better materials or build quality, but Kef have created an amp specifically matched for the LS50 driver which is superior by design. It's designed to drive one load and one load only, and is not an easy one to drive as all my different amp demos have taught me.The actives are bi-amped, active crossover, 230wpc with DSP.

How was the sound? Absolutely phenomenal. Beyond breathtaking, and it moved me to my core. Compared to the passives driven by the Naim Nait 5si, Rega Elex-R and Cyrus One (the amps I've didn't most time with), it just blows them all away without breaking a sweat. It's not even close, a landslide victory. The LS50W was far more transparent, more dynamic, more true to the sound. The clarity was incredible. The soundstage was bigger too. Imaging was much better and genuinely holographic. I did a side by side demo and the LS50W makes the passives sound downright flat and 2D. Switch back to the LS50W and it's like you've activated the 3D switch. By far and away the biggest improvent is the bass. The bass is so much better. It's much deeper, hitting a solid 40hz (compared with the 70 I was measuring on the passives + Naim). It's more textured, detailed and rythmic. Incredible for such a small driver. It was shocking to hear how much musical information and impact I had been missing with the passives. The midrange is clear and more transparant, and the highs are just as brilliant. Overall the ls50W was more revealing, less bright, with better tonality across the entire spectrum. It felt like the LS50s just got the perfect amp pgrade. After so many combinations it finally felt like it all clicked into place.

The built in streamer works well with tidal and Spotify connect. The DSP is easy to use and is a great ear to adjust the sound to your taste. Im currently using it in stand mode set to free space, running 6+ dB bass boost with 'extra' bass extension. I vary the treble trim from -1.5db to 0 dB bass on my mood and song choice.

I can't recommend the LS50W enough. They are my endgame for a long timetim I know it's need to spend so much more to get any incremental upgrades. The only thing I will add at some point is a sub. I tried them with a REL 7ti and they were fantastic. Really gets that last octave out there. I've also added some GIK acoustic panels and I couldn't be happier with the sound.

The LS50W is by far the best value of any ls50 combination I've heard to date. You just won't bear it for the price. You would need to spend so much money to even come close with the passives. If you are considering the LS50, try and book a demo to hear the wireless before you get the passives. If you have the passives and you like what you hear then you could consider a trade in or sell the seperates to get the wireless. This is just my impression, but I would encourage you to hear for yourself.

So it finally feels like my upgrade journey with the KEF is over. I don't regret that I bounced around with so many amps as I enjoy the journey. In the egg me though I'm happy to have arrived at the destination i wanted. If I ever move on from the LS50s it would most certainly be to a different speaker entirely. A fantastic speaker from KEF, and an even better sequel to the original
View attachment 1106884 View attachment 1101575

Hey everyone,

EDIT: This review is getting quite long now as I've added to it with every upgrade in chronological order. Initially I start with the LS50s driven by the Cyrus One, before comparing the Rega Elex-R and Naim Nait 5si in depth. At the bottom you will find my review of the LS50W actives which is where my upgrade path led me and what I currently own.





I've bought the LS50s a few months ago and absolutely loving them. They are an amazing pair of speakers for the price.

i just wanted to note some observations and impressions regarding amp choices (~£700-£1500) after many demos. I was a bit overwhelmed with options at first so hopefully this will help inform someone else's choice.

For reference in my demos my chain was KEF LS50 < *AMP* < Chord 2Qute DAC < Tidal Hifi. At home i use Atacama Moseco 6 stands filled all the way with atabites ontop of granite slabs in a small/medium sized room.

Initial choice:

- Cyrus One (£699) -
This is the amplifier i initially brought with my LS50s at a decent discount as part of my LS50 Package. I got the standard version without digital inputs (which retails at £999)
The extensive list of features was nice to have, even though i didn't use a lot of them. The headphone output works well enough, but is unremarkable. The phone remote control app was really useful though, and a good thing too because the remote is terrible.

At 100Wpc class D they drove the LS50s comfortably and with authority. The bass response was very powerful with a decent amount of tightness and texture. The amp was an excellent all rounder for its price. I felt it did everything quite well (compared to others of its price). lacking and excelling at nothing in particular, it just got on with it and made everything sound decent. it could pretty much handle every genre of music reasonably well, and also sounded good with regular TV viewing.
The sound signature was very lively and entertaining. It captures attention immediately has a high level of engagement and enthusiasm. Over time i actually found that the sound was a bit too forward, and always demanding for attention. This was particularly true for voices. Although this prominence is at first appealing for vocal or acoustic music, after a while it got a bit fatiguing.
The tonality seemed overall well balanced, neither too bright or warm with a decent but no excessive amount of air and sparkle. The soundstage was big enough compared to similarly priced amps but nothing astonishing. Detail and rhythm were i felt a bit lacking. I felt there were likely entire layers of the music missing from the the presentation and the timing was offset.

This reason combined with the fact that the input signal was occasional clipped (the Cyrus One has a max input of 2.5V RMS while my DAC outputs at an unusually high 3V RMS) i decided to sell the amp and upgrade it. I still think that its a very good all rounder and i would still recommend it for the LS50s.

So having decided to now upgrade my Cyrus One, i was looking for amps in the price range of £700-1500. I wont review them all, but have listed them below. After many in-store demos I eventually narrowed it down to two, but the runners up were:
(Ranking is very approximate as i could not A/B all of them against east other)

1. Roksan K3 (£1300)
2. Quad VA One (£1299)
3. Musical Fidelity M3si (ertainly be to a different speaker entirely. A fantastic speaker from KEF, and an even better sequel to the original
First of all thanks for the review. Very detailed and helpful.

Ive recently bought a pair of black edition LS50'S passives and I'm looking for an amp in the £600-1000 range. Your review has helped me narrow it down to the Cyrus One, the Rega and the Naim you reviewed. I'm being swayed towards the rega at the moment although the Cyrus One HD is tempting as it has a built in DAC which I do not own. If I use chrome cast from my phone to the amp will I be using my phones DAC or the amps?

I'd get the active LS50'S but I want a seperate amp incase I want to change speakers in the future. Are you sure the naim is powerful enough at 60 wpc. Compared to the Cyrus at 100wpc seems like I could be future proofing myself with the Cyrus incase I ever wanted floorstanders
 

gibbsy

Moderator
First of all thanks for the review. Very detailed and helpful.

Ive recently bought a pair of black edition LS50'S passives and I'm looking for an amp in the £600-1000 range. Your review has helped me narrow it down to the Cyrus One, the Rega and the Naim you reviewed. I'm being swayed towards the rega at the moment although the Cyrus One HD is tempting as it has a built in DAC which I do not own. If I use chrome cast from my phone to the amp will I be using my phones DAC or the amps?

I'd get the active LS50'S but I want a seperate amp incase I want to change speakers in the future. Are you sure the naim is powerful enough at 60 wpc. Compared to the Cyrus at 100wpc seems like I could be future proofing myself with the Cyrus incase I ever wanted floorstanders
I was disappointed with how the Naims failed to control the bass on my KEF R300s, not quick enough, couldn't hear the individual chords. No such problems with a Rega, dynamic and showed great control. I'd push your budget and get an Elex-R.
 

nygafre

Novice Member
I know this is an old thread. But..
As I own the Rega Elex-R and also previously the Chord Dac, I suspect that the brightness the OP experienced with the Elex-R/2Qute/LS50s-combo were caused by the 2Qute DAC, and/or the speakers. (The OP also states that the 2Qute could be bright at times). Maybe it's a synergy thing. I do not find the Elex-R bright/metallic with the speakers I have tested.
Aside from that I have no problems accepting that people could find the Naim amp preferable to the Rega. But I would never classify the Rega as piercy or edgy.
 
Hate to go off art a tangent but I had cyrus7 bi amp bi wired set up and looked at Rega Naim etc. I ended up going for KEF LS50w. Never considered active speakers before but well impressed with set up so far. Rational was that KEF have done all the matching of amp to speaker so no more issues with amp cable compatibility and the added connectivity via wifi is proving useful with my data base of FLAC files and spotify lists
 

The latest video from AVForums

Movies Podcast: Star Trek in 4K. Is the new boxset worth it?
Subscribe to our YouTube channel

Full fat HDMI teeshirts

Support AVForums with Patreon

Top Bottom