Both are Arcam, from different ranges - the engineering approach is shared and the differences are mostly in power, connectivity and price.
| 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 Arcam A25 for a large room and 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 increases strongly (150W and 165W). |
| Noise floor | evenly matched | Much the same signal-to-noise ratio (106dB vs 106dB). |
| Built-in DAC | B | Both decode on board. Arcam A25 goes higher - 384kHz against 192kHz. Very few recordings exist above 192kHz, so treat this as headroom, not as sound quality. |
| Analogue inputs | A | Arcam SA20 takes more analogue sources - 4 against 3. |
| Room to grow | evenly matched | The same expansion options on both. |
| Price | B | Arcam A25 costs less - $1,499 against $1,650 at list. |
A Arcam SA20 B Arcam A25
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?
Neither runs away with it - they trade advantages. Let the "depends" rows and the speakers you already own settle it.
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.