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 | B | Sony STR-DH190 has more power - 90W against 60W into 8 ohms. That is about 1.8dB, which is a small step in loudness but real headroom on peaks. |
| Built-in DAC | A | Yamaha A-S301 has a DAC on board; the other needs an external one, which is another box, another power lead and another purchase. |
| Room to grow | A | Only Yamaha A-S301 offers preamp outputs - which decides whether you can add a subwoofer or a power amplifier later without replacing the box. |
| Shelf space | depends | Sony STR-DH190 takes up about 24% less shelf area (1299cm² against 1701cm²), and it is 89mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | Sony STR-DH190 costs less - $248 against $350 at list. |
| Watts per dollar | B | Sony STR-DH190 is the cheaper watt - about $3 per watt against $6. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Yamaha A-S301 B Sony STR-DH190
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. If you already own a DAC or a streamer, the built-in one is money you are paying twice for, and Sony STR-DH190 becomes the more rational buy. Think about the whole system: the roughly $102 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.