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 | JBL MA510 has more power - 75W against 50W into 8 ohms. That is about 1.8dB, which is a small step in loudness but real headroom on peaks. |
| Analogue inputs | A | Marantz NR1510 takes more analogue sources - 3 against 2. |
| Phono stage | depends | Marantz NR1510 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. |
| Built-in sources | depends | Marantz NR1510 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 | Marantz NR1510 is AB and JBL MA510 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. |
| Price | B | JBL MA510 costs less - $660 against $700 at list. |
| Watts per dollar | B | JBL MA510 is the cheaper watt - about $9 per watt against $14. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Marantz NR1510 B JBL MA510
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 MA510 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, Marantz NR1510 saves you buying a phono stage; if you do not, ignore that row entirely.
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.