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Musical Fidelity M5si Integrated Strongman

In the 1980’s World’s Strongest Man competition, the UK’s Geoff Capes was used to doing well. Twice a winner and regularly top of his game. Built like the proverbial brick something house, tossing Mini Cooper’s over and pulling jet aeroplanes, making Michael Douglas’ anger in the film Falling Down, look subdued and pedestrian.

Analogies to HiFi would make him a Bryston 28B³ power amp or Hegel’s top H30 amp. Fire, Frenzy and authoritatively muscular as far as audio goes. The Musical Fidelity M5si is a more toned down everyday Strongman, fitting a bigger range of ‘consumer’ audiophile speakers – maybe contextualized to the other lower weight Strongman classes. A Porsche to drive to the shops, not that I’ve ever owned one – the Porsche I mean. But all these analogies fit, because where is it common to find such power – 150W at 8ohms of power – in such a small integrated box, or at this price?

All the M-Series models are inspired by the previous Titan design – the word Titan being another clue as to what Musical Fidelity is all about and keeping my theme here. Musical Fidelity’s Anthony Michaelson seems not to buy into the idea of low power output particularly when you look at the M-Series and what went before. Like M-Series with BMW: powerful.

Musical Fidelity M5si Review
Musical Fidelity M5si Review

A class AB amp also offers the right balance of tone as well as price and fidelity. No potential for insidious Class-D treble. Plus keeping distortion low whilst having the power enabling dynamic headroom to make the music more Yello then Mellow Yellow is definitely what the design is about here, Musical Fidelity say – not the bit about musical preference!! I’m with this logic since, generally, when do you hear quality amps sound as capable as less powerful ones. Forget age old ‘true to form’ forum discussion about 40watt amps being all you need to drive speakers, with volume and speaker sensitivity in mind….this is about Dynamics with a capital D. But with rooms often being bigger and listening distances being further apart nowadays……..well, it all makes sense. 

Musical Fidelity play so much heed to power output that they are in the process of reintroducing a “calculator” that Anthony Michaelson used to use many years ago, to help customers calculate what they perceive would be an ideal power range to consider in their next amplifier.

Musical Fidelity M5si Review
Musical Fidelity M5si Review

Another big clue to what this amp is about, chiming to my experience of listening to it, is when being told by the distributor; “M-Series is an exercise in exploring the concept that with power comes ‘Comfort’.” For this is one aspect of listening to this amp. Comfort is one way of describing the tonal mass present – it is thick and rich** and with a big powerful bass. Musical Fidelity even say themselves this amp has this extended bass, so no manufacturer hype here. Play any type of electronic or acoustic music and this bass becomes abundantly clear. Also there is a big soundstage** with depth and presence and the ‘Musical’ in Musical Fidelity is true to form with the required symbiotic relationship of sound quality to sound ‘size’. The M5si maybe wouldn’t be a fit for ‘leanists’, but it sure will suit more tastes than not! So a match for neutral or lean speakers, but not overly toned, so as to hit the neutrality bullseye.

The treble is not in your face, but in the short time I listened to this amp I got a strong impression it sits perched topside. Not some pretentious bird simile? Wait – I’ll explain….I mean no bleeding of the treble into the midrange, but keeping the higher frequencies relative to extremes. In the marketing it is described as ‘crystalline’, which kind of gets to the same adage.

motorized volume dial
Musical Fidelity M5si Review
Musical Fidelity M5si Review

Musical Fidelity make a point that obsessions with power are not an end game and this amp is not a one trick pony, this way. It it well designed too with a pretty conventional case but with slabbed aluminium sides – a generous doorstep loaf of bread to the conventional thin danish ‘ply metal’ loaf….so more than you expect with some amps in a similar price bracket, in other words. To say that it is heavy for its size would not be obvious on eyeballing the M5si. Maybe not for Geoff Capes but if you moved it enough times in some weird strongman relay, you’d know.

Also the M5si utilises a single circuit board with two independent mono block power amps and a pre amp. Whether this could technicality be classed as ‘dual mono’ I’m not sure, but looking at the way the power amps are demarcated on the board, well designed channel separation seems to be going on, so another upstroke. Musical Fidelity consider it similar in technical performance to the gutsier M6si.

binding posts of M5si amp
Musical Fidelity M5si Review

To the sceptics, a lot of what I might have said here might sound like marketing speak, for it ain’t because this isn’t even an official review – the M5si was brought around by a follower to my YouTube Channel. It’s fair to say that when you press the on button and rotate that large chunky motorized volume dial clockwise, there is nothing untoward with this amplifier. Exactly as I was expecting from the reputation of this brand, and as Thom Yorke once said ; “No surprises

This amp is definitely a “saver-upper” to the less luxurious and lower priced thinner sounding £1300 Cyrus One Cast Integrated amplifier and more authoritative with scale and muscle to a Marantz PM7000N streaming integrated. Admittedly the Cyrus has its own distinct dynamic advantage on side with its high damping class D. Also too, that the M5si is not a streaming Integrated but a dedicated Integrated amp.

Solid case of Musical Fidelity M5si amp
case is well built and heavy

It is also more wider set in its scale and authority to a similarly priced Hegel H120 I tried it against. The Hegel has it over the Musical Fidelity in areas such as dynamic intonation with bass and midrange, utilizing the brilliant hybrid Class AB SoundEngine2 technology Hegel use, which involves a different means of amplifier feedback. The Musical Fidelity has the tonal thickness to mask the start and stop of the bass notes that you just don’t find in Hegel amps with bass being more on and off. Which is more natural to you will be a question of preference and choice, but whatever, this thickness is definitely one the designers had in mind with the M5si. At half the power, the Hegel H120 cannot create the same soundscapes and only on trying the much improved and more powerful H390, is the Musical Fidelity outdone in this area. That all said, remember the Hegel is a streaming amp (with Spotify Connect) and with more digital inputs than USB, substantiating higher price.

Musical Fidelity M5si casework

The M5si was designed at a time around 2015 when the market demand for DACs inside Integrated amps was not there, so you do not get any digital inputs other than USB. Most of the money appears to have gone into the amp and case and this is how the M5si should be viewed I think. There is a moving magnet phono stage input, you get 4 analogue inputs and there is fixed line level outs, so you could use this Musical Fidelity in a home cinema system to drive front channels. Alternatively variable line level pre-outs to use the M5si’s volume control and add another power amp, with an appropriate switch to select means of operation, respectively. Incidentally I’d prefer a more robust protected switch to avoid inadvertent switching and damage to speakers! Finally, you get a single set of speaker binding posts and in and out 3.5mm trigger inputs to turn the M5si on by other components, or use the M5si to do so.

I didn’t have the time to make DAC comparisons but on accounts of the owner, the DAC is acceptable if not shouting from the rooftops. But in light of the design elements I’ve mentioned this is probably no big news.

Analogue inputs of Musical Fidelity M5si amp

The bottom line is that if the requirement is high power, no thrills, tonal mass and soundstage and you are using more modern DACs or streaming DACs elsewhere in the chain already, or using it for vinyl, the M5si comes recommended.

Using my original tag line, this amp justly and credibly stacks up to its reputation as that middle weight Strongman for Audiophiles with everyday speakers that need to be driven really well.

(**stand out sonic traits in bold, as ever!)


Musical Fidelity :
Distributed in the UK by Henley Audio :

Binding posts - single set - M5si


  • Power Output : 150W @ 8ohms
  • THD (+noise): <0.010% typical 20Hz – 20kHz
  • S/N Ratio : >100dB ‘A’ – weighted
  • Frequency Response : +0, -0.1dB, 10Hz to 20kHz
  • Inputs : 4x Line Level RCA
  • Digital Input – 1x USB B : Asynchronous stream up to 24/96
  • 1 x MM phono input
  • Trigger In & Out
  • Fixed Line level Outs
  • Variable preamp out
  • Input selections – front input push buttons / remote
  • Dimensions : WxHxD (mm) L 440 x 100 x 405
  • Weight unpacked : 14.6kg
Musical Fidelity Logo



Testing Equipment

PMC twenty5 23 speakers, IsoTek Aquarius Power Conditioner, Hegel H390 Amplifier,  Hegel H120 Amplifier, Chord Qutest DAC with linear PSU, RME ADI-2 DAC FS DAC, Bluesound Node 2i Streamer, Innuos Zenith mk2, Innuos PhoenixUSB re-clocker.

More from Musical Fidelity: MX-DAC see here

Musical Fidelity MX-DAC

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Written by Simon Price

I'm music lover who shares experiences of faithfully reproduced audio in an ENGAGING way with HIGH VIDEO PRODUCTION VALUES. I enjoy and make reviews as I love audio gadgets, being a voice on audio and producing creative videos that ultimately benefit the industry and new participation. I keep technicalities easy, as I believe great audio serves music and music is inclusive and to be enjoyed by all!

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