Both are JBL, from different ranges - the engineering approach is shared and the differences are mostly in power, connectivity and price.
| Area | Better | Why |
|---|
| Power | B | JBL MA710 has more power - 110W against 75W into 8 ohms. That is about 1.7dB, which is a small step in loudness but real headroom on peaks. |
| Analogue inputs | evenly matched | The same number of line-level inputs (2). |
| Phono stage | depends | JBL MA710 has a built-in phono stage and JBL MA510 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. |
| Price | A | JBL MA510 costs less - $660 against $880 at list. |
A JBL MA510 B JBL MA710
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?
JBL MA710 is ahead, but on only 1 of the measured areas, and it costs about 33% more. That is a lot of money for a narrow margin - JBL MA510 is the sensible buy unless a specific feature above decides it for you. If you play records, JBL MA710 saves you buying a phono stage; if you do not, ignore that row entirely. Think about the whole system: the roughly $220 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.