Different price classes - Arcam SA20 costs roughly 1.8x what Yamaha A-S801 does. Expect it to lead on paper; the question is whether you will hear the difference through the speakers you own.
| Area | Better | Why |
|---|
| Power | evenly matched | Effectively the same output - 90W against 100W into 8 ohms is under 1dB, which is not an audible difference in loudness. |
| Room size | depends | We rate Arcam SA20 the better fit for a small room, and Yamaha A-S801 for a large room and a very large room. Match the amplifier to the room you actually have, not the one you want. |
| Noise floor | A | Arcam SA20 is the quieter design on paper - 106dB against 99dB. Audible mainly with sensitive speakers in a quiet room. |
| 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. |
| Amplifier class | depends | Arcam SA20 is Class G and Yamaha A-S801 is Class A/B. Class G/H switches its supply rails to cut the heat a Class A/B design wastes; Class A/B runs warm and is the long-established mainstream choice. Modern examples of both measure well - judge by the rest of the page. |
| Price | B | Yamaha A-S801 costs less - $900 against $1,650 at list. |
| Watts per dollar | B | Yamaha A-S801 is the cheaper watt - about $9 per watt against $18. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Arcam SA20 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 is the easier recommendation: it leads on most of the measured areas and costs less. Take Arcam SA20 if one of the "depends" rows above describes your system. Think about the whole system: the roughly $750 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.