Musical Fidelity M6 500i Integrated Amplifier Review

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Absolute power corrupts - but it doesn’t distort.

by Ed Selley Mar 1, 2019 at 8:23 AM

  • SRP: £3,499.00

    What is the Musical Fidelity M6 500i?

    The Musical Fidelity M6 500i is an integrated amplifier and part of a range of M6 components. These are notable because they are at once new and not new. Thanks to the takeover of Musical Fidelity by Pro-Ject last year, the M6 family has re-entered production after initially being discontinued by Musical Fidelity. As such, it gives us the opportunity to look at the 500i as the chance passed me by originally.

    The reason why this is a relevant amp to look at is threefold. First up, it is a chance to look at what this money gets you in amplifier terms if you forgo digital inputs, UPnP modules and other modern trimmings and just focus on the business of building an amplifier. Secondly, as I have some experience of the ‘original’ version of this amp, it gives us the chance to see if the Pro-Ject takeover has had any discernible effect on the qualities we associate with a Musical Fidelity amp.

    Thirdly, this represents another opportunity for a teachable moment. A question that is frequently asked on the forum is ‘How much power do I need?’ The M6 500i has a rather singular answer to this question and as well as judging the amp on its own merits, we can look at the reality of answering this question with a very large number indeed. The only thing left to do is put some music on and look for some answers.

    Specification and Design

    Musical Fidelity M6 500i Specification and Design
    The M6 500i is part of the M6 family of devices. These comprise the M6si integrated amplifier and an M6 Pre and power amp as well as a CD player and standalone DAC. The most notable thing that you will note when looking at the amplifier specifications between the M6si and M6 Pre and then the M6 500i is that they don’t make a huge amount of sense on paper. For £2,499, the M6 Si has a phono stage that supports moving magnet and moving coil phono cartridges and a USB input that can handle digital files up to 24/96. The Preamp is similarly equipped.

    The M6 500i by contrast doesn’t have anything like as many features. There is no phono stage or digital input. You get five line inputs, one on XLR and the rest on RCA. There is a record out and a pre-out. That is your lot. Given that it costs £1,000 more than the rather better equipped M6si, this can seem a little parsimonious. The reason for this disparity is simple though, the M6 500i is a lot more amplifier. By way of hurried reference, the M6si is no shrinking violet in this regard. It will deliver a healthy 220 watts into 8 ohms which is pretty powerful by most normal standards. The M6 power amplifier will give you even more - 230 watts into the same 8 ohm load. The M6 500i makes them look a bit feeble though because it disposes of no less than 500 watts into an 8 ohm load.

    For the avoidance of doubt, this is not a figure plucked out of thin air and neither is it creative license. The M6 500i does not deliver this figure as a freak squawk just before it melts and the number is given as RMS not PMPO. It isn’t generated by a class D amplifier and it hits that figure at less than 0.1% distortion. This genuinely is an amplifier that will deliver half a kilowatt of amplified power into a pair of speakers, if you wish to do so.
    Musical Fidelity M6 500i Specification and Design
    This, of course, leads to a perfectly reasonable follow-up question - why? After all, I’ve just done a quick cycle through every speaker I have reviewed for AVForums since I began reviewing here in 2012 and not one of them makes the claim of being able to handle such a biblical figure. The reasoning behind the M6 500i isn’t simply to turn anything you connect to it into a puddle of molten slag but is instead one of dynamics. When listening to music at a given volume level, the demands made of the amp are not constant. Dynamic peaks (‘loud bits’) are going to need more power than the little intro bit with a solitary guitar and quiet vocals. The realism of the performance, in part, depends on the amplifier’s ability to respond to these requests for more power. From here, it is a hop, skip and a jump to building an amplifier that can handle any such request with massive margin to spare.

    To create this hefty output, the M6 500i is effectively two mono channels and a preamp shoehorned into a single chassis. Each channel has its own (large) toroid to feed it and the preamp lives above them like a mezzanine. There’s no magic at work here. You can recognise all the components you would in a more conventionally rated amplifier but they’re all quite a bit bigger. Testimony to the materials used is that the Musical Fidelity tips the scales at 30kg which when taken against the size of the chassis gives it the density of a neutron star.

    Musical Fidelity M6 500i
    There are some reassuring signs that Musical Fidelity knows what they are doing though. The volume control is on a rotary encoder which means that there is rather more than a single rotation to deploy the power. There are also some very extensive heatsinks on either side of the chassis - in fact, roughly one third the volume of the amp is heatsink. This means it runs surprisingly cool in use. In fact, in terms of living with one, provided you don’t herniate yourself getting it out of the box, it is amazingly benign to live with.

    The aesthetics of the M6 500i convey a very simple message and that message is ‘I AM VERY POWERFUL.’ In the black finish especially, it looks like it has been made from things that Musical Fidelity found in a storage hut behind Lockheed Martin. I try to stay above the idea that audio equipment has any gender focus to it but there’s little arguing that the M6 500i conveys a fairly masculine aesthetic. It is well made too, the volume control has a lovely heft to it and it feels immensely solid. The Pro-Ject takeover hasn’t resulted in the factory where the Musical Fidelity is built being changed and this one feels every bit as hefty as the sample I spent some time with in 2010. Only the remote lets the side down a little. It is also unchanged and feels a little lightweight and confusingly laid out.

    One very notable aspect of the change to the new ownership and distribution though is the price. When the M6 500i originally appeared in 2011, it cost £3,999 and this price crept up over the years. This one, eight years later and totally identical costs £3,499. This means that in a world where the price of almost everything else has crept up it has to be seen as bit of a bargain.

    Musical Fidelity M6 500i
    The aesthetics of the M6 500i convey a very simple message and that message is ‘I AM VERY POWERFUL.’

    How was the M6 500i Tested?

    The Musical Fidelity has been used with a Naim ND5 XS2 network streamer, taking a feed from a Melco N1A NAS drive and a Rogue Audio Triton II phono stage running off a Michell Gyrodec turntable with SME M2-9 arm and Hana EL cartridge. All equipment has run off an IsoTek Evo 3 Aquarius Mains conditioner. The speakers used have been the Acoustic Energy AE1 Classic, Neat Momentum 4i and Monitor Audio Gold 100. Material used has included FLAC, AIFF, DSD, some Tidal and Deezer as well as some vinyl.

    Sound Quality

    Musical Fidelity M6 500i Sound Quality
    Let’s get something out of the way first. I’m betting a few people reading this will have made an assumption - subconscious or otherwise - that living with a 500 watt amplifier in a domestic setting is going to look a bit like this. Am I right? If I am, firstly you’re showing your age by remembering that and secondly, it isn’t like that. I can state with some confidence that using the M6 500i is no harder than any other integrated amp I’ve tested in the last decade. ‘But surely’ you respond, ‘you need to be careful not to blow your speakers?’ Again, not really and if that sounds bizarre, let me try to explain.

    First up, due to the fitment of devices called ‘ears’ to either side of your head, you have the means of working out when you are pushing your speakers too hard as they will give a fair amount of audible warning. The second point is that the most common cause of damage to speakers is not overdriving them with too much power but damaging them when you push an amplifier too hard and it induces distortion which is, in turn, sent to the speaker. As the conditions under which the M6 500i will do this are very limited, it can instead ensure that your speakers are fed a lovely distortion free dollop of power. Finally, that encoder volume control ensures that setting the correct level is simplicity itself - there’s no hair trigger element to this.

    So, we’ve established what it won’t do but what are the realities of using half a kilowatt? The key word here is ‘effortless.’ I started my listening with my resident pair of Acoustic Energy AE1 Classics. This is an urgent little speaker, demanding on amps and prone to sounding edgy if they aren’t up to the job. Connected to the M6 500i, they are able to deliver their speed and sheer musical joy but the forwardness is gone from the mix. They slam through Feral Roots by Rival Sons with everything I love about them clear as day but pretty much all their downsides nullified.

    Trying to describe the effect of applying this much power to music is maddeningly hard but the key sentiment that any description has to feature goes back to that feeling of effortlessness. The M6 500i can take any piece of music you can think of and deliver it with an eye opening lack of compression. Even when you were previously unaware of there being any curtailment to dynamics, the effect of applying the Musical Fidelity to the same music is still profound at times. It’s akin to taking a filter out of the presentation and letting things breathe better.
    Musical Fidelity M6 500i Sound Quality
    The effect it has on bass response is also noteworthy. Even through the dinky AE1, a speaker that is constrained by physics to bottoming out at around 50Hz, still feels like it has gained an octave. Through the rather heftier Neat Momentum, the experience is profound. There are very few amplifiers below £5,000 that ‘do bass’ like this one does. The best part of this is that it’s simply there as the lower frequency response, it doesn’t truly register how good it is until you switch back to a ‘normal’ amp.

    The rest of the M6 500i’s tonal balance might be best described as fractionally on the bright side of neutral. With a very forward speaker, this might be an issue for the most part, it feels really well judged. The stunningly bleak Nocturnal Sunshine by the band of the same name is given a slightly human quality that really helps the level of listener engagement without drastically altering the tonal balance. This is helped once again by the power output. All too often I write something like ‘pushed hard, it hardens up’ but the reality of life with 500 watts at your disposal is that pushing the M6 500i hard enough to see that happen is going to need an enormous room, a very hefty pair of speakers indeed and no neighbours.

    This untrammelled power means that for every standard listening experience, from Sunday morning jazz to drunken singing along to power ballads, is done in completely within the comfort zone of the herculean amplification section. I’ve tried to stay away from car analogies but it has to be likened to driving at 75mph in a two cars, one capable of 90mph and one capable of 200mph. The reserves in hand with the latter make for a rather more relaxed experience. Of course, it is only fair to point out that like running a 200mph car, there are some additional running costs to consider. As the not terribly proud owner of a pay as you go electricity meter at the moment, I can confirm that running an amp with a notional maximum power consumption of 2,000 watts does have a noticeable effect on your electricity bill. Should the long threatened energy consumption stickers make their way to Hi-Fi, I suspect that a new multiple of Z will need to be found for it.

    Musical Fidelity M6 500i
    The M6 500i can take any piece of music you can think of and deliver it with an eye opening lack of compression


    OUT OF


    • Accurate, refined and exciting sound
    • Unlimited headroom
    • Very well made


    • Slightly limited spec
    • Prodigious power consumption
    • Fussy remote
    You own this Total 0
    You want this Total 1
    You had this Total 0

    Musical Fidelity M6 500i Integrated Amplifier Review

    The M6 500i is an unusual amplifier and one that needs a little contextualising. Compared to some of the other models available for this price, it can seem absurdly minimalist, lacking many of the features we are coming to expect on stereo integrated designs. Against this, what you are offered in return is a power figure that seems utterly ridiculous for home use. In a world outside of playground Top Trumps, it seems like a blow dealt for nothing. That the new owners of Musical Fidelity have decided to resurrect it seems even more peculiar.

    As I hope, the rest of the review has shown, the reality is rather different. As people often lament, the idea of true transparency in two channel is often rarer than many would like. This is a 30kg, aesthetically imposing riposte to that complaint. The operating envelope of the M6 500i is so enormous that for any (that’s right, I’m using an absolute) domestic situation, what you will get is exactly what is sent. This means that partnered with similarly capable components such as the Chord Qutest and Q Acoustics Concept 500, you’d have a system that would be utterly accurate - a genuine ‘window on the music’ - for dramatically less than such a system would normally cost you. The M6 500i is one of the all-time great integrated amplifiers and the fact it is back at a lower price than it has ever been before means that this time, it can earn a Highly Recommended accolade.

    Suggested retail price when reviewed: £3,499.00

    The Rundown

    Build Quality




    Ease of use




    Audio quality


    Value for money




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