These are not the same size of amplifier: Marantz PM-10 has roughly 2x the power of Marantz Model 30. That is about 3dB, so it is a question of room size and how hard your speakers are to drive, not of one being the better amplifier.
| Area | Better | Why |
|---|
| Power | B | Marantz PM-10 has more power - 200W against 100W into 8 ohms. That is about 3dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Room size | depends | We rate Marantz Model 30 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 (200W and 400W). |
| Noise floor | B | Marantz PM-10 is the quieter design on paper - 111dB against 88dB. Audible mainly with sensitive speakers in a quiet room. |
| Analogue inputs | A | Marantz Model 30 takes more analogue sources - 6 against 5. |
| Room to grow | A | Only Marantz Model 30 offers preamp outputs - which decides whether you can add a subwoofer or a power amplifier later without replacing the box. |
| Price | A | Marantz Model 30 costs less - $2,999 against $8,999 at list. |
| Watts per dollar | A | Marantz Model 30 is the cheaper watt - about $30 per watt against $45. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Marantz Model 30 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 Model 30 has the edge on paper, though not by much. The rows marked "depends" are more likely to decide this than the score is. 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, 100 watts is already more than most people ever use, and the extra 100 watts would be headroom you pay for and never hear - we rate Marantz PM-10 poorly for near-field use for exactly that reason. Think about the whole system: the roughly $6,000 saved by taking the cheaper one would buy better speakers or a subwoofer, which does more for the sound than the difference between two competent amplifiers.
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.