One is a streaming all-in-one and the other is an amplifier. Judge them on how many boxes you want and what you already own, not on the spec sheet alone.
| Area | Better | Why |
|---|
| Power | B | Sonos Amp has more power - 125W against 100W into 8 ohms. That is about 1dB, which is a small step in loudness but real headroom on peaks. |
| Noise floor | B | Sonos Amp is the quieter design on paper - 116dB against 99dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | A | Both decode on board. Yamaha A-S801 goes higher - 384kHz against 44kHz. Very few recordings exist above 192kHz, so treat this as headroom, not as sound quality. |
| Streaming | evenly matched | Only Sonos Amp has AirPlay 2. Neither list is longer in a way that matters - check the one service you actually pay for. |
| Analogue inputs | A | Yamaha A-S801 takes more analogue sources - 6 against 1. |
| Phono stage | depends | Yamaha A-S801 has a built-in phono stage (MM) and Sonos Amp 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. |
| Room to grow | evenly matched | The same expansion options on both. |
| Headphones | depends | Only Yamaha A-S801 has a headphone output. Worth something if you listen late, nothing if you never do. |
| Amplifier class | depends | Yamaha A-S801 is Class A/B and Sonos Amp 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 | Sonos Amp takes up about 71% less shelf area (518cm² against 1792cm²), and it is 174mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | Sonos Amp costs less - $699 against $900 at list. |
| Watts per dollar | B | Sonos Amp is the cheaper watt - about $6 per watt against $9. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Yamaha A-S801 B Sonos Amp
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?
Sonos Amp has the edge on paper, though not by much. The rows marked "depends" are more likely to decide this than the score is. If you play records, Yamaha A-S801 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.