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 MA9100HP has more power - 140W against 100W into 8 ohms. That is about 1.5dB, which is a small step in loudness but real headroom on peaks. |
| Analogue inputs | A | Anthem MRX 540 8K takes more analogue sources - 5 against 2. |
| Phono stage | depends | JBL MA9100HP has a built-in phono stage and Anthem MRX 540 8K 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 | A | Only Anthem MRX 540 8K offers preamp outputs - which decides whether you can add a subwoofer or a power amplifier later without replacing the box. |
| Amplifier class | depends | Anthem MRX 540 8K is AB+D and JBL MA9100HP is D. 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 MA9100HP costs less - $1,760 against $1,900 at list. |
| Watts per dollar | B | JBL MA9100HP is the cheaper watt - about $13 per watt against $19. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Anthem MRX 540 8K B JBL MA9100HP
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 play records, JBL MA9100HP 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.