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. |
| Use with a TV | depends | Only Arcam SA45 has HDMI eARC, so the television can drive it directly and one remote controls the volume. If the system is for music only, this changes nothing. |
| 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. If this sits under a television, Arcam SA45 is the one to buy - HDMI ARC means the TV remote controls the volume and there is no second box in the way.
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.