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 | Yamaha A-S801 has more power - 100W against 60W into 8 ohms. That is about 2.2dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Room size | depends | We rate Rotel A12 the better fit for desk or near-field listening and a small room, and Yamaha A-S801 for a mid-size room, a large room and a very large room. Match the amplifier to the room you actually have, not the one you want. |
| Noise floor | evenly matched | Much the same signal-to-noise ratio (100dB vs 99dB). |
| Built-in DAC | B | Both decode on board. Yamaha A-S801 goes higher - 384kHz against 192kHz. Very few recordings exist above 192kHz, so treat this as headroom, not as sound quality. |
| Analogue inputs | B | Yamaha A-S801 takes more analogue sources - 6 against 4. |
| Room to grow | evenly matched | The same expansion options on both. |
| Price | A | Rotel A12 costs less - $800 against $900 at list. |
| Watts per dollar | B | Yamaha A-S801 is the cheaper watt - about $9 per watt against $13. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Rotel A12 B Yamaha A-S801
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?
Yamaha A-S801 leads across most of the measured areas for a fairly modest premium, so it is the easier pick if the budget stretches. Rotel A12 is the one to take if it does not. 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 - Yamaha A-S801 has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 60 watts is already more than most people ever use, and the extra 40 watts would be headroom you pay for and never hear - we rate Yamaha A-S801 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.