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 | evenly matched | Effectively the same output - 50W against 55W into 8 ohms is under 1dB, which is not an audible difference in loudness. |
| Speaker load rating | B | Yamaha WXA-50 is rated down to 4 ohms against 8, so it is the safer partner for a low-impedance speaker. |
| Noise floor | B | Yamaha WXA-50 is the quieter design on paper - 110dB against 90dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | B | Both decode on board, but only Yamaha WXA-50 handles DSD. |
| Analogue inputs | A | Rotel A10 MKII takes more analogue sources - 4 against 1. |
| Phono stage | depends | Rotel A10 MKII has a built-in phono stage (MM) 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 and a subwoofer output - which decides whether you can add a subwoofer or a power amplifier later without replacing the box. |
| Headphones | depends | Only Rotel A10 MKII has a headphone output. Worth something if you listen late, nothing if you never do. |
| Amplifier class | depends | Rotel A10 MKII 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 65% less shelf area (572cm² against 1633cm²), and it is 111mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | evenly matched | Priced within a few per cent of each other. |
A Rotel A10 MKII 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?
Yamaha WXA-50 has the edge on paper, though not by much. The rows marked "depends" are more likely to decide this than the score is. If you play records, Rotel A10 MKII 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.