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 - 55W against 60W into 8 ohms is under 1dB, which is not an audible difference in loudness. |
| Noise floor | A | Yamaha WXA-50 is the quieter design on paper - 110dB against 100dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | A | Both decode on board, but only Yamaha WXA-50 handles DSD. |
| Analogue inputs | B | Rotel A12 takes more analogue sources - 4 against 1. |
| Phono stage | depends | Rotel A12 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 | evenly matched | The same expansion options on both. |
| Headphones | depends | Only Rotel A12 has a headphone output. Worth something if you listen late, nothing if you never do. |
| Amplifier class | depends | Yamaha WXA-50 is Class D and Rotel A12 is Class A/B. Class D runs cool and draws almost nothing at idle; Class A/B runs warm and is the long-established mainstream choice. 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 | A | Yamaha WXA-50 costs less - $599 against $800 at list. |
A Yamaha WXA-50 B Rotel A12
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 A12 saves you buying a phono stage; if you do not, ignore that row entirely. Think about the whole system: the roughly $201 saved by taking the cheaper one would buy better speakers or a subwoofer, and either 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 interface feels 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.