These are not the same size of amplifier: Marantz Model 10 has roughly 2.5x the power of Marantz Model 30. That is about 4dB, 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 Model 10 has more power - 250W against 100W into 8 ohms. That is about 4dB, 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 Model 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 500W). |
| Bass control | evenly matched | Similar damping factor (500 vs 500). |
| Noise floor | B | Marantz Model 10 is the quieter design on paper - 122dB against 88dB. Audible mainly with sensitive speakers in a quiet room. |
| Analogue inputs | evenly matched | The same number of line-level inputs (6). |
| Room to grow | B | Only Marantz Model 10 offers a pre-out/main-in loop - 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 $15,000 at list. |
| Watts per dollar | A | Marantz Model 30 is the cheaper watt - about $30 per watt against $60. 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 Model 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?
The usual trade-off: Marantz Model 10 measures better, Marantz Model 30 costs about 80% less. With most speakers in most rooms that gap is smaller in practice than it looks here. 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 Model 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 150 watts would be headroom you pay for and never hear - we rate Marantz Model 10 poorly for near-field use for exactly that reason. Think about the whole system: the roughly $12,001 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.