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 | Cambridge Audio AXR100 has more power - 100W against 55W into 8 ohms. That is about 2.6dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Built-in DAC | B | Both decode on board, but only Yamaha WXA-50 handles DSD. |
| Phono stage | depends | Cambridge Audio AXR100 has a built-in phono stage and Yamaha WXA-50 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 Yamaha WXA-50 offers preamp outputs - which decides whether you can add a subwoofer or a power amplifier later without replacing the box. |
| Amplifier class | depends | Cambridge Audio AXR100 is Class A/B and Yamaha WXA-50 is Class D. Class A/B runs warm and is the long-established mainstream choice; Class D runs cool and draws almost nothing at idle. Modern examples of both measure well - judge by the rest of the page. |
| Shelf space | depends | Yamaha WXA-50 takes up about 64% less shelf area (572cm² against 1591cm²), and it is 103mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | Yamaha WXA-50 costs less - $599 against $699 at list. |
| Watts per dollar | A | Cambridge Audio AXR100 is the cheaper watt - about $7 per watt against $11. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Cambridge Audio AXR100 B Yamaha WXA-50
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?
Neither runs away with it - they trade advantages. Let the "depends" rows and the speakers you already own settle it. 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 - Cambridge Audio AXR100 has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 55 watts is already more than most people ever use, and the extra 45 watts would be headroom you pay for and never hear. If you play records, Cambridge Audio AXR100 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.