Musical Fidelity M8xi Integrated Amplifier Review

For when 500 watts just isn’t enough

by Ed Selley
SRP: £5,649.00

Introduction - what is the M8xi?

The Musical Fidelity M8xi is an integrated amplifier and one of the first new designs to appear since the company was purchased by Pro-Ject Audio Systems in 2019. If we look past the more arresting aspects of its specification (which, I assure you, we’ll cover thoroughly), it is competing in the same hotly contested field as a few designs we’ve looked at in recent years. These amps are expected to offer connectivity sufficient to handle whatever spread of analogue and digital inputs you might have to hand and perform admirably with all of them.

The M8xi is part of the 8 Series of components intended to be the highest specification, solid state devices in the Musical Fidelity range, below the hybrid NuVista models. As well as the integrated amp, there is a preamp with mono and stereo power amp options. There is, of course, a supporting selection of components from the 6 Series and MX range to add functionality too. Such is the way that these overlapping ranges work, you can mix them together in a way that should suit almost all requirements.

But… this is window dressing to an extent isn’t it? Plenty of rivals have connectivity similar to the M8xi. Some of them have the same overlapping range too. Rather fewer of them possess a specification quite like this one though. So, what is this remarkable device like to live with? Read on to find out.

Specification and Design 

Musical Fidelity M8xi
The front panel is clean and uncluttered

Not too long ago (March 2019), I reviewed the M6 500i. This is a member of the M6 range and combines a selection of analogue inputs with an amplifier section that can deliver 500 watts of sustained output power. It takes a special sort of company to stand back, look at their handiwork and go, “well, it could do with a bit more power” but Musical Fidelity did just that and here we are.

The M8xi delivers 550 watts into 8 ohms. Again, to ensure there’s no ambiguity about this, that figure is continuous, given in RMS (no PMPO or some other spurious measurement) and at a quoted distortion figure negligible enough to have two zeroes after the decimal point. This figure rises to 870 watts into four ohms and 1.6kW into two. The limitations of the amount of electricity available to it via the UK mains preclude a full and unconstrained attack on one ohm but, the M8Xi is stable into such a load nonetheless. What’s more, information I’ve seen from two sources who have benched the M8xi suggest that these figures are actually on the pessimistic side. However you look at it, this is a biblically powerful amplifier. I am not aware of any stereo pair of speakers, domestic or professional, dynamic driver or otherwise, that will present a challenge to the M8xi.

This begs the same question as before; why? The philosophy behind this enormous power output lies in the idea of dynamic peaks. For the majority of time an amp is playing into a pair of speakers under normal domestic listening conditions, the power required for playback is not high. There are dynamic points in the music though that will make spontaneous demands for more amplifier power. The argument with these Musical Fidelity designs is not that you’ll be routinely chucking 550 watts at your speakers but that, when these peaks appear, the power in reserve and ready to go just like that is beyond any realistic requirements the music might have, which ensures you are adequately covered off.

Musical Fidelity M8xi
Connectivity is more extensive than the stripped back M6 500i

The internal layout of the M8Xi is similar to the ‘smaller’ M6 500i. Internally, it is effectively two monoblocks and a preamp amp; all separately powered and given their own board space. The bottom of the internal space has a pair of toroids for the power amps which are placed vertically on the sides of the chassis backing on to the heatsinks. The preamp is class A biased and, like the M6 500i, uses a rotary encoder rather than a conventional pot to get the power down. This means that the M8xi has much more than a single rotation to go from mute to full which - when you consider the power available - is beneficial.

Of course, there’s more to the M8xi than the power output. The simplest way to show this is in the - possibly unheralded but useful nonetheless - measurement of pounds per watt. The M6 500i, even at its current price of £3,999, delivers a pounds per watt figure of £7.99. Even with an extra 50 watts at its disposal, this increases in the M8xi to £10.29 (this is still huge bang for buck incidentally, by way of reference, the Cambridge Audio Edge A after its recent price rise to £5,500 comes in at £55 per watt). The reason for this is that the M6 500i is the minimum of frippery required for you to make use of that enormous amplifier. The M8xi is rather more ornate.

This means that you get two XLR inputs, four RCA inputs (one with an AV bypass), tape and preout connections, the latter on XLR and RCA. This is joined by a digital board that has two optical, two coaxial and one USB connection. This is an unusual thing in 2020 in that it isn’t an ESS Sabre based board. Instead Musical Fidelity has stuck with the Burr Brown PCM 5242 that they’ve used in a few applications. This does mean that there’s no DSD support to be had here. The M8xi offers 24/192kHz PCM as a maximum which might leave you questioning why Musical Fidelity went to the effort (we’ll hopefully cover off that a little later). There is no phono stage or headphone amp either, although Musical Fidelity does make a wide selection of both.

Musical Fidelity M8xi
The remote is classic Musical Fidelity

All this comes wrapped in casework that is - and there’s no point beating around the bush at this point - massive. The M8xi is a very nearly half a metre wide, over half a metre deep and nearly 20 centimetres high. I don’t recall testing an AV receiver as large as this one. It also weighs 41kg. Having trouble imagining that sort of weight? It’s the sort that ensures that an osteopath gets to send you a Christmas card every year for the rest of your life. Unless you powerlift in your spare time, this is not a one person lift. This is also not an amp that you should buy assuming it will ‘probably fit.’ I’d suggest measuring, then measuring again.

It is well made though and the cleanliness of the styling helps (a little) to mask the bulk. Despite doing more than the M6 500i, the M8xi is actually simpler in terms of front panel layout. This is dominated by a pair of rotary controls, one for volume and one for input selection. These flank a white on black display which shows input and volume. There are two small buttons, one of which turns the Musical Fidelity on and the other that dims the display. There is a supporting remote handset that, in the great Musical Fidelity tradition, has many buttons, not all of which pertain to the amp and that don’t necessarily do the function you’d expect.

Musical Fidelity M8xi
 

All this comes wrapped in casework that is - and there’s no point beating around the bush at this point - massive

How was the M8xi tested?

Unusually for the review process of any mains voltage product in this system, the Musical Fidelity was not connected to a mains conditioner. The reason for this is that the M8xi has a 16A IEC connection and technically, its peak power requirements exceed that of any of the conditioners present. With this in mind - even though the likelihood of actually hitting this figure was low - I connected directly to a wall socket. It has been tested with a Chord Electronics Hugo TT2 DAC and Hugo Mscaler running from an SOtM SMS 200 Neo being used as a Roon Endpoint. This SOtM has also been connected to the USB input and a coax feed has been taken from the Mscaler. Speakers used have been the Kudos Titan 505 and Focal Kanta No1. Material used has been FLAC, AIFF, Tidal and Qobuz.

More: Audio Formats

Performance

Musical Fidelity M8xi
Even in a large rack, the M8xi is a tight fit

Just in case you haven’t read the M6 500i review (shame on you), let’s clear something up right at the start. Living with a 550 watt amp is not like life with a car where the cruise control is jammed at 120mph or trying to barbecue with a smelter. The use of the rotary encoder means that you can set the volume level you want and the range of adjustment is pretty extensive. Living with the M8xi is no trickier than any other amp you’ve seen reviewed here.

That volcanic power output does make itself felt though. Initially bypassing the internal decoding and using the Chord duo, listening to the opening of Public Service Broadcasting’s Every Valley via the Kudos is a reminder of the sheer heft that this amp possesses. The Titan 505 does not lack for bass in any context yet, improbably, the M8xi finds more heft and reach from them than I’ve had before. The deep electronic synth line at the start of The Pit becomes something that hovers on the edge of going subsonic.

And it’s effortless. It’s hard to get into words just how incredibly free of any sense of strain or limitation this amp is. Even in comparison with the resident Chord CPM 2800 MkII and Edge A, the Musical Fidelity will take on pretty much anything you can think of and relay it with an absolute absence of constraint. It does mean that a degree of care is needed day to day. Our volume cues are derived largely from distortion. As the Musical Fidelity doesn’t distort in any meaningful way under domestic use, you can find yourself running this amp very loud indeed.

There are some differences between the M8xi and the M6 500i though. The first is that this larger amp feels more nimble and light on its feet. It has a skill with timing that I’ve not previously encountered with any of the very high power designs. It also has a rather greater ability to sound small. This might sound ridiculous but if you listen to something like My Baby’s Tribulations, Cato Van Dyck should not sound like she’s eight feel tall with lungs the size of phone boxes. In the hands of the M8xi, she has the dimensions and the delicacy that the piece needs.

Musical Fidelity M8xi
Black is also available 

Then, there’s the digital section. By rights, this elderly DAC chip should be viewed as a convenience feature; something up to the job of accepting your TV signal. There is though, a little more to it than that. The tonal balance of this digital section is superbly judged against the tone of the amp. There is a fractional brightness to the top end that adds a little speed and bite to the presentation. This is an area of subjectivity that you can take or leave but, used within its performance envelope, there are times where it is a truly perfect match for the rest of the M8xi.

It isn’t perfect though. Shorn of the effortless ‘digital can opener’ of the Chord pairing, the M8xi has a soundstage that never sounds small but lacks the airiness and scale that some other amps can generate (although, it is completely unfazed by the volume you choose and at the point where rivals are starting to run out of puff, it sounds exactly the same. Interestingly, using the Mscaler on its own and using it to cycle material to 176.4/192kHz before sending to the Musical Fidelity brings some of this space back, so it’s possible that tinkering with DSPs in the digital domain might help here.

The chances are though that your desire to ‘tinker’ will be secondary to wanting to listen. Like the M6 500i, once you dial into the way that this amp makes music, it is something you find yourself listening to for hours at a time. It can’t be easily wrongfooted and there’s the all important joy to using it that marks out great Hi-Fi. One other aspect of the performance that is worthy of note is that the Musical Fidelity is fairly unfussy about what you partner with it. Substituting the Focal for the Kudos still sees this amp do what it does without serious alterations to the presentation. Using a 550 watt amp with a speaker as sensitive as the Focal might sound like a recipe for hair trigger volume control but, as noted, it doesn’t work like that. In a way, it’s a shame that the Bowers 702 Signature had gone home by the time this arrived as I suspect that this would be a very capable partner for them.

Musical Fidelity M8xi
A heavyweight champ
 

It’s hard to get into words just how incredibly free of any sense of strain or limitation this amp is

Verdict

Pros

  • Absolutely effortless scale, power and dynamics
  • Suprisingly fast and rhythmic
  • Well made and handsome

Cons

  • Enormous
  • Heavy
  • Some rivals have better digital sections

Musical Fidelity M8xi Integrated Amplifier Review

On paper, the M8xi exists to crack a very particular nut. It can drive any speaker to any level domestic or otherwise and do so with an effortlessness that is fairly addictive. The thing is, if this is the itch you need scratching, you can save £1,650 and buy the M6 500i which can do the same thing. The justification for the larger amp is something that makes itself felt the more time you spend with it. This is a more rounded performer than the 500i. It has nuances that the cheaper amp lacks and it can do things both with tempo and delicacy that I’ve not experienced from Musical Fidelity’s ‘super amps’ before. This monster of an amplifier is something that can demonstrate some decidedly cuddly attributes when called upon to do so and, so long as you can accommodate its prodigious bulk, it is something that comes Highly Recommended.

Highly Recommended

Scores

Build Quality

.
9

Connectivity

.
.
8

Ease of use

.
.
8

Features

.
.
8

Audio quality

.
9

Value for money

.
9

Overall

.
9
9
AVForumsSCORE
OUT OF
10

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