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 | A | Sony STR-DH590 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. |
| Speaker load rating | B | JBL MA310 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 2. |
| Room to grow | evenly matched | The same expansion options on both. |
| Built-in sources | depends | Sony STR-DH590 has a radio tuner built in. That is one less box if you still play discs or listen to radio, and dead weight if you do not. |
| Amplifier class | depends | Sony STR-DH590 is AB and JBL MA310 is 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 | Sony STR-DH590 takes up about 21% less shelf area (1318cm² against 1672cm²), and it is 80mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | JBL MA310 costs less - $440 against $498 at list. |
| Watts per dollar | A | Sony STR-DH590 is the cheaper watt - about $6 per watt against $7. 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 JBL MA310
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?
The usual trade-off: Sony STR-DH590 measures better, JBL MA310 costs about 12% less. With most speakers in most rooms that gap is smaller in practice than it looks here.
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.