These are not the same size of amplifier: Arcam SA45 has roughly 3.6x the power of Arcam SA10. That is about 5.6dB, 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 | B | Arcam SA45 has more power - 180W against 50W into 8 ohms. That is about 5.6dB - a different class of amplifier rather than a bigger version of the same one, and far more than most rooms will ever ask for. |
| Grip on hard loads | evenly matched | Both behave much the same into 4 ohms - output increases strongly (85W and 300W). |
| Noise floor | B | Arcam SA45 is the quieter design on paper - 110dB against 106dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | B | Both decode on board. Arcam SA45 goes higher - 384kHz against 192kHz. Very few recordings exist above 192kHz, so treat this as headroom, not as sound quality. |
| Streaming | B | Only Arcam SA45 has AirPlay 2, Chromecast and Roon. |
| Room to grow | evenly matched | The same expansion options on both. |
| Room correction | B | Arcam SA45 has room correction. In an awkward room that does more for the sound than any other difference on this page. |
| Headphones | depends | Only Arcam SA10 has a headphone output. Worth something if you listen late, nothing if you never do. |
| Amplifier class | depends | Arcam SA10 is Class A/B and Arcam SA45 is Class G. Class A/B runs warm and is the long-established mainstream choice; Class G/H switches its supply rails to cut the heat a Class A/B design wastes. Modern examples of both measure well - judge by the rest of the page. |
| Shelf space | depends | Arcam SA10 takes up about 15% less shelf area (1523cm² against 1796cm²), and it is 63mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | A | Arcam SA10 costs less - $880 against $5,500 at list. |
| Watts per dollar | A | Arcam SA10 is the cheaper watt - about $18 per watt against $31. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Arcam SA10 B Arcam SA45
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?
The usual trade-off: Arcam SA45 measures better, Arcam SA10 costs about 84% less. With most speakers in most rooms that gap is smaller in practice than it looks here. 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 SA45 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 130 watts would be headroom you pay for and never hear. Think about the whole system: the roughly $4,620 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.