One is a streaming all-in-one and the other is an amplifier. Judge them on how many boxes you want and what you already own, not on the spec sheet alone.
| Area | Better | Why |
|---|
| Power | B | Yamaha A-S501 has more power - 85W against 55W into 8 ohms. That is about 1.9dB, which is a small step in loudness but real headroom on peaks. |
| Room size | depends | We rate Yamaha WXA-70A the better fit for desk or near-field listening and a small room, and Yamaha A-S501 for a mid-size room, a large room and a very large room. Match the amplifier to the room you actually have, not the one you want. |
| Built-in DAC | A | Both decode on board, but only Yamaha WXA-70A handles DSD. |
| Streaming | A | Only Yamaha WXA-70A has AirPlay 2, Chromecast and Roon. |
| Analogue inputs | B | Yamaha A-S501 takes more analogue sources - 6 against 1. |
| Phono stage | depends | Yamaha A-S501 has a built-in phono stage (MM) and Yamaha WXA-70A 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 Yamaha A-S501 has a headphone output. Worth something if you listen late, nothing if you never do. |
| Shelf space | depends | Yamaha WXA-70A takes up about 66% less shelf area (587cm² against 1710cm²), and it is 126mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | Yamaha A-S501 costs less - $550 against $1,300 at list. |
| Watts per dollar | B | Yamaha A-S501 is the cheaper watt - about $6 per watt against $24. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Yamaha WXA-70A B Yamaha A-S501
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-S501 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, Yamaha A-S501 saves you buying a phono stage; if you do not, ignore that row entirely. Think about the whole system: the roughly $750 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.