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 95W into 8 ohms. That is about 1.7dB, which is a small step in loudness but real headroom on peaks. |
| Analogue inputs | A | Denon AVR-X2900H takes more analogue sources - 4 against 2. |
| Room to grow | evenly matched | The same expansion options on both. |
| Built-in sources | depends | Denon AVR-X2900H 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 | Denon AVR-X2900H is AB and JBL MA9100HP 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 | Denon AVR-X2900H takes up about 15% less shelf area (1559cm² against 1837cm²), and it is 67mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | A | Denon AVR-X2900H costs less - $1,349 against $1,760 at list. |
A Denon AVR-X2900H 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.
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.