No single best amplifier here. What decides it is what you have to drive, what you need to plug in, and how much of the system you want in one box.
| Area | Better | Why |
|---|
| Power | B | Marantz MODEL M1 has more power - 100W against 76W into 8 ohms. That is about 1.2dB, which is a small step in loudness but real headroom on peaks. |
| Room size | depends | We rate Musical Fidelity M2si the better fit for a small room, and Marantz MODEL M1 for a large room and a very large room. Match the amplifier to the room you actually have, not the one you want. |
| Grip on hard loads | A | Musical Fidelity M2si holds up better into a 4-ohm load: its output nearly doubles to 137W, where the other increases modestly. That matters with demanding speakers far more than the 8-ohm figure does. |
| Built-in DAC | B | Marantz MODEL M1 has a DAC on board; the other needs an external one, which is another box, another power lead and another purchase. |
| Analogue inputs | A | Musical Fidelity M2si takes more analogue sources - 5 against 3. |
| Phono stage | depends | Musical Fidelity M2si has a built-in phono stage (MM) and Marantz MODEL M1 does not. Decisive if you own a turntable, completely irrelevant if you do not - and an outboard phono stage is easy to add later either way. |
| Use with a TV | depends | Only Marantz MODEL M1 has HDMI eARC, so the television can drive it directly and one remote controls the volume. If the system is for music only, this changes nothing. |
| Amplifier class | depends | Musical Fidelity M2si is Class A/B and Marantz MODEL M1 is Class D. Class A/B runs warm and is the long-established mainstream choice; Class D runs cool and draws almost nothing at idle. Modern examples of both measure well - judge by the rest of the page. |
| Shelf space | depends | Marantz MODEL M1 takes up about 69% less shelf area (552cm² against 1760cm²), and it is 147mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | Marantz MODEL M1 costs less - $1,000 against $1,299 at list. |
| Watts per dollar | B | Marantz MODEL M1 is the cheaper watt - about $10 per watt against $17. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Musical Fidelity M2si B Marantz MODEL M1
depends neither is better in the abstract - it turns on your room, your system or how you will use them. Only specs published for both amplifiers are judged; anything missing on either side is left out rather than guessed.
Which should you choose?
Marantz MODEL M1 has the edge on paper, though not by much. The rows marked "depends" are more likely to decide this than the score is. If your speakers are a difficult load - 4 ohms nominal, big woofers, or a sensitivity in the low 80s - Musical Fidelity M2si is the safer partner, because how an amplifier behaves when the impedance drops matters more than its 8-ohm rating. If you play records, Musical Fidelity M2si saves you buying a phono stage; if you do not, ignore that row entirely.
What a spec sheet cannot show: how either sounds with your speakers, how the controls feel day to day, and what the app is like to live with - which is where most all-in-one amplifiers are actually won or lost. Power figures are the manufacturers' own and are not measured to a common standard, so treat small differences as noise. If you can hear both, that will tell you more than any row above.