Different price classes - Yamaha RX-V6A costs roughly 1.7x what Sony STR-DH590 does. Expect it to lead on paper; the question is whether you will hear the difference through the speakers you own.
| Area | Better | Why |
|---|
| Power | evenly matched | Effectively the same output - 90W against 100W into 8 ohms is under 1dB, which is not an audible difference in loudness. |
| Speaker load rating | B | Yamaha RX-V6A is rated down to 4 ohms against 6, so it is the safer partner for a low-impedance speaker. |
| Analogue inputs | A | Sony STR-DH590 takes more analogue sources - 4 against 3. |
| Phono stage | depends | Yamaha RX-V6A has a built-in phono stage and Sony STR-DH590 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. |
| Shelf space | depends | Sony STR-DH590 takes up about 20% less shelf area (1318cm² against 1651cm²), and it is 73mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | A | Sony STR-DH590 costs less - $498 against $850 at list. |
| Watts per dollar | A | Sony STR-DH590 is the cheaper watt - about $6 per watt against $9. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Sony STR-DH590 B Yamaha RX-V6A
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?
Sony STR-DH590 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 RX-V6A saves you buying a phono stage; if you do not, ignore that row entirely. Think about the whole system: the roughly $352 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.