No single best amplifier here. What decides it is what you have to drive, what you need to plug in, and how much of the system you want in one box.
| Area | Better | Why |
|---|
| Power | A | Arcam A15 has more power - 80W against 60W into 8 ohms. That is about 1.2dB, which is a small step in loudness but real headroom on peaks. |
| Room size | depends | We rate Arcam A15 the better fit for a mid-size room, a large room and a very large room, and Cambridge Audio CXA61 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 (120W and 90W). |
| Noise floor | evenly matched | Much the same signal-to-noise ratio (106dB vs 105dB). |
| Built-in DAC | B | Both decode on board. Cambridge Audio CXA61 goes higher - 384kHz against 192kHz. Very few recordings exist above 192kHz, so treat this as headroom, not as sound quality. |
| Analogue inputs | B | Cambridge Audio CXA61 takes more analogue sources - 5 against 3. |
| Phono stage | depends | Arcam A15 has a built-in phono stage (MM) and Cambridge Audio CXA61 does not. Decisive if you own a turntable, completely irrelevant if you do not - and an outboard phono stage is easy to add later either way. |
| Room to grow | B | Only Cambridge Audio CXA61 offers a subwoofer output - which decides whether you can add a subwoofer or a power amplifier later without replacing the box. |
| Price | A | Arcam A15 costs less - $999 against $1,099 at list. |
| Watts per dollar | A | Arcam A15 is the cheaper watt - about $12 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 A15 B Cambridge Audio CXA61
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: Cambridge Audio CXA61 measures better, Arcam A15 costs about 9% less. With most speakers in most rooms that gap is smaller in practice than it looks here. If you play records, Arcam A15 saves you buying a phono stage; if you do not, ignore that row entirely.
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.