Different price classes - Cambridge Audio CXA81 costs roughly 1.7x what Yamaha A-S801 does. Expect it to lead on paper; the question is whether you will hear the difference through the speakers you own.
| Area | Better | Why |
|---|
| Power | B | Yamaha A-S801 has more power - 100W against 80W into 8 ohms. That is about 1dB, which is a small step in loudness but real headroom on peaks. |
| Room size | depends | We rate Cambridge Audio CXA81 the better fit for a small room, and Yamaha A-S801 for a large room and a very large room. Match the amplifier to the room you actually have, not the one you want. |
| Noise floor | A | Cambridge Audio CXA81 is the quieter design on paper - 105dB against 99dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | evenly matched | Both have a DAC on board with much the same capability. |
| Analogue inputs | B | Yamaha A-S801 takes more analogue sources - 6 against 5. |
| Phono stage | depends | Yamaha A-S801 has a built-in phono stage (MM) and Cambridge Audio CXA81 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 | evenly matched | The same expansion options on both. |
| Price | B | Yamaha A-S801 costs less - $900 against $1,499 at list. |
| Watts per dollar | B | Yamaha A-S801 is the cheaper watt - about $9 per watt against $19. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Cambridge Audio CXA81 B Yamaha A-S801
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?
Yamaha A-S801 is the easier recommendation: it leads on most of the measured areas and costs less. Take Cambridge Audio CXA81 if one of the "depends" rows above describes your system. If you play records, Yamaha A-S801 saves you buying a phono stage; if you do not, ignore that row entirely. Think about the whole system: the roughly $599 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.