Pro-ject acquired Musical Fidelity in mid 2018 with the first fruits of the venture, the M2si integrated (£799 / US$1099 / €899) launched later that year. Which makes the amplifier over 5 years old, begging the question ‘why on earth review it now?’ Heck it doesn’t have digital inputs, there’s no phono stage, and as for a headphone output….. 

Well that’s sort of the point. Sticking to a ‘straight’ amplifier means you’re not tied to any one DAC, streamer, phono stage or headamp. Bring your own devices, with no need to park elements of the amplifier, ones you’ve paid for, when the inevitable upgrade comes. Amplifier technology progresses slowly, invest wisely and make obsolescence but a faint glimmer on the horizon. 

Which all assumes a good sounding amplifier of course. The Musical Fidelity M2si first impressed when reviewing Monitor Audio speakers. Soon after, Klipsch RP-600M II standmounts went under the microscope. In need of a price-appropriate amplifier I blagged an M2si to play with them; it impressed again. So when the speakers went back I kept hold of the amplifier for its own review. And here we are, 3 months down the line, the M2si having been used in numerous settings. Let’s just say we got to know each other well.

What you get

Facilities are straightforward, based around a core of six line inputs. One is switchable to bypass the pre-amplifier stage and use the M2si purely as a power amp; handy for audio-video setups. You could also use it in the future with a preamp / DAC / streamer that has its own volume control.

There are two outputs, the first being fixed-level for a tape recorder, headphone amplifier or similar. The other is variable, for use with an external power amplifier or (more likely) to connect a subwoofer into your system. RCA sockets are prevalent, the M2si eschewing balanced (XLR) connection (fair enough at this price level). A single set of speaker terminals completes the line up. Like I said, the M2si is simple. 

The amplifier runs in Class A/B and outputs 72wpc into 8Ω, nearly doubling to 137wpc into 4Ω (mfr spec) – plenty for most reasonably sensitivite speakers. At 9.2kg the M2si is also quite heavy – usually a sign of good transformers – and can deliver 25 amps peak to peak current, which isn’t bad. Damping factor is a deliberately low 36 though; hold that thought. 

Attention has been paid to the oft-overlooked volume control, an item that can impact sound quality significantly. From Musical Fidelity’s website: –

“For best low channel volume matching we employ a high quality Burr-Brown stepped attenuator delivering performance way above that of conventional potentiometer designs”

A remote control handles input switching and volume control. Plus functionality for other devices such as the matching M2SCD CD player. It’s fussy and lightweight but no more so than equivalent remotes.

Finally, in the UK a WiiM Mini is included within the £799 price (check the score in your geography.) As a concept it’s neat, we’re big fans of WiiM at Hifi Starters. The Mini’s internal DAC is only so-so though. Better to use the WiiM Pro Plus with it’s higher quality DAC, as we did for this review. Maybe time to brush up on those haggling skills?

Looks & build quality

The M2si’s layout and looks are simple. A large central volume knob is flanked by six small buttons to select the source, LEDs showing which is in use, and a small power switch sits on the left. The body of the amplifier is black, choose between silver or black for the front panel. The overall vibe is discrete and understated. 

The M2si is really nicely put together too, the front panel fashioned from aluminium and feeling solid to the touch. The steel casework of the amplifier is also appropriately stiff, and everything fits together well. All of which combine to make the M2si look and feel like a much more expensive amplifier.


Core listening was via Graham LS6 (£2,400) standmount speakers, with and without a REL T/7x (£999) subwoofer. Source was the WiiM Pro Plus (£220) used mainly via a Mytek Liberty II DAC (1,295.)

The M2si also saw service with Pro-ject Stream Box S2 Ultra and Bluesound Node streamers, and Klipsch RP-600M II and Elac B6.2 speakers.


In whatever context, the M2si put in a consistently good performance, working chameleon-like to bring out the best in partnering equipment (speakers in particular). Unlike some amplifiers that exert more of their own character (my Marantz PM6006 for one). 

The M2si’s sound was also powerful and dynamic, bass in particular having real depth and weight, if lacking a little control. And whilst treble was slightly muted, the M2si missing a little air and sparkle against some, the main takeaway was of a really well-balanced amplifier. 

Delving deeper, the M2si’s bass underpinned a big sound. Queen’s Made In Heaven may suffer from overzealous mastering but it didn’t half burst from the speakers; pomp and majesty reigned (sic) down. “I’m In Love With My Car” from A Night at the Opera was similarly bombastic, the M2si’s dynamics making themselves known. 

Ambient electronic fayre was particularly well served, the M2si’s low bass and ability to throw a big, deep soundstage combining for a really atmospheric sound. Bersarin Quartett’s new album Systeme was a good example, the M2si conveying a beautiful ripeness to the sound as it wafted around me. Likewise Sabi from Eraldo Bernocchi and Hishiko Yamane (the latter now of Tangerine Dream). A new find for me – I’ll be investigating their 2020 Mujo soon – the heft delivered by the M2si was truly impressive. The cones of the Grahams got a real workout. 

The slight ripeness derives from the M2si’s low damping factor, meaning it exerts less control over the speaker cones; they overshoot slightly rather than starting/stopping quickly. In theory that muddies the bass slightly but with the M2si it translated to a benign warmth low-down, which made for an engaging listen. As intended by the designer, who voiced the M2si and its big brother M3si that way (I asked).

At the top end, treble was slightly rolled off but this didn’t seem to impact the soundstage, nor the M2si’s retrieval of detail. True performers weren’t pinpointed quite as precisely within the soundstage as some, but that didn’t trouble me. And the slightly soft treble did make the M2si forgiving of poor recordings, like the aforementioned Queen tracks. Even the Klipsch RP-600M II standmounts couldn’t be tempted into harshness, something other amplifiers can struggle with. The M2si also gave the Klipsch some much-needed body without detracting from the speaker’s innately live sound. 

Overall the M2si had real substance. Full-fat sound, not semi-skimmed. A double espresso not a single. Good old-fashioned custard, the sort your mum would make, not the lighter creme-Anglaise (which I’m actually rather partial to.) Choose your analogy, you get the gist. 


Against a £420 Rega io – in for review as part of Rega’s System One – the M2si showed what spending more brings. 

Through the Klipsch RP-600M II standmounts Neil Cowley’s ‘Chance’ on Fragmented Recall sounded much lighter with the Rega. The soundstage through the M2si was bigger, deeper, more ethereal. There was more body to the sound too, a richer tone. And better bass, the M2si digging deeper, sounding fuller. 

With Semyon Bychkof & the Czech Philharmonic’s Mahler 1 a similar story panned out. There was a much broader sweep of sound from the M2si, with greater depth. The top end was sweeter and more refined, most notably on violins. All in all there was a better sense of the huge forces playing in front of me.

Overall the M2si had a more mature sound, the delta between the amps more marked than the £300 price difference might suggest 

Against my venerable Ayre AX-7e the tables were turned. 

On the Neil Cowley track the Ayre advanced things further. Bass went notably deeper, although like the M2si it wasn’t overly taut. I was left marvelling at what the AX-7e could coax out of the Klipsch though. The Ayre also retrieved more detail, showing just how much was going on in the track. The same was true with the Mahler, which was even more expansive with the AX-7e. 

Unlike the Rega, the Ayre had a similar sonic character to the M2si, it just did everything better. As you’d expect; the AX-7e would probably cost 4-5 times as much were it sold today. The M2si wasn’t embarrassed by the comparison, but nor were any giants slain. 


Sometimes you have to step back from the wood to see the trees. The M2si’s frequency extremes may deviate slightly from neutrality but I for one liked the weighty yet agile sound it produced. A lot – the M2si rather got under my skin over the extended period it was here.

Taken as a whole it delivered a performance belying its entry-level status in the Musical Fidelity range. Instead there was a maturity to the sound that impressed deeply in the long term. It worked well with all the partnering equipment I threw at it. Speakers in particular got a sympathetic hearing, the M2si teasing out their strengths rather than imposing its own character. 

Add in understated but stylish looks and good build quality and you have an amplifier that fully justifies its asking price. Age is but a number they say; ignore it I say. Indeed I can see the M2si forming the core of many excellent systems, whether for Hifi Starters or those further along the path. An Editor’s Choice award is therefore a formality.

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