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 PM-10 has more power - 200W against 125W into 8 ohms. That is about 2dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Room size | depends | We rate MOON 641 the better fit for desk or near-field listening, a small room and a mid-size room, and Marantz PM-10 for a very large room. Match the amplifier to the room you actually have, not the one you want. |
| Grip on hard loads | evenly matched | Both behave much the same into 4 ohms - output nearly doubles (250W and 400W). |
| Noise floor | evenly matched | Much the same signal-to-noise ratio (109dB vs 111dB). |
| Analogue inputs | evenly matched | The same number of line-level inputs (5). |
| Headphones | depends | Only Marantz PM-10 has a headphone output. Worth something if you listen late, nothing if you never do. |
| Amplifier class | depends | MOON 641 is Class A/B and Marantz PM-10 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. |
| Price | B | Marantz PM-10 costs less - $8,999 against $11,000 at list. |
| Watts per dollar | B | Marantz PM-10 is the cheaper watt - about $45 per watt against $88. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A MOON 641 B Marantz PM-10
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 PM-10 is the easier recommendation: it leads on most of the measured areas and costs less. Take MOON 641 if one of the "depends" rows above describes your system. Start with the room. In a large or open-plan room, or with speakers that are hard to drive - low sensitivity, or an impedance that dips - Marantz PM-10 has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 125 watts is already more than most people ever use, and the extra 75 watts would be headroom you pay for and never hear - we rate Marantz PM-10 poorly for near-field use for exactly that reason.
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.