These are not the same size of amplifier: Arcam A25 has roughly 2x the power of Arcam SA10. That is about 3dB, 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 | A | Arcam A25 has more power - 100W against 50W into 8 ohms. That is about 3dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Room size | depends | We rate Arcam A25 the better fit for a mid-size room, a large room and a very large room, and Arcam SA10 for desk or near-field listening and a small 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 (165W and 85W). |
| Noise floor | evenly matched | Much the same signal-to-noise ratio (106dB vs 106dB). |
| Built-in DAC | A | 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 | B | Arcam SA10 takes more analogue sources - 4 against 3. |
| Room to grow | evenly matched | The same expansion options on both. |
| Amplifier class | depends | Arcam A25 is Class G and Arcam SA10 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 | Arcam SA10 costs less - $880 against $1,499 at list. |
A Arcam A25 B Arcam SA10
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?
Arcam A25 is ahead, but on only 1 of the measured areas, and it costs about 70% more. That is a lot of money for a narrow margin - Arcam SA10 is the sensible buy unless a specific feature above decides it for you. 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 - Arcam A25 has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 50 watts is already more than most people ever use, and the extra 50 watts would be headroom you pay for and never hear - we rate Arcam A25 poorly for near-field use for exactly that reason. Think about the whole system: the roughly $619 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.