These are not the same size of amplifier: Denon Home Amp has roughly 2x the power of Denon PMA-900HNE. That is about 3dB, so it is a question of room size and how hard your speakers are to drive, not of one being the better amplifier.
| Area | Better | Why |
|---|
| Power | A | Denon Home Amp has more power - 100W against 50W into 8 ohms. That is about 3dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Grip on hard loads | B | Denon PMA-900HNE holds up better into a 4-ohm load: its output increases strongly to 85W, where the other increases modestly. That matters with demanding speakers far more than the 8-ohm figure does. |
| Built-in DAC | evenly matched | Both have a DAC on board with much the same capability. |
| Streaming | evenly matched | Only Denon PMA-900HNE has Roon. Neither list is longer in a way that matters - check the one service you actually pay for. |
| Phono stage | depends | Denon PMA-900HNE has a built-in phono stage (MM,MC) and Denon Home Amp 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. |
| Amplifier class | depends | Denon Home Amp is Class D and Denon PMA-900HNE is Class A/B. Class D runs cool and draws almost nothing at idle; Class A/B runs warm and is the long-established mainstream choice. Modern examples of both measure well - judge by the rest of the page. |
| Shelf space | depends | Denon Home Amp takes up about 66% less shelf area (580cm² against 1710cm²), and it is 127mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | A | Denon Home Amp costs less - $899 against $949 at list. |
| Watts per dollar | A | Denon Home Amp is the cheaper watt - about $9 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 Denon Home Amp B Denon PMA-900HNE
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?
Denon Home Amp has the edge on paper, though not by much. The rows marked "depends" are more likely to decide this than the score is. If your speakers are a difficult load - 4 ohms nominal, big woofers, or a sensitivity in the low 80s - Denon PMA-900HNE is the safer partner, because how an amplifier behaves when the impedance drops matters more than its 8-ohm rating. Start with the room. In a large or open-plan room, or with speakers that are hard to drive - low sensitivity, or an impedance that dips - Denon Home Amp has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 50 watts is already more than most people ever use, and the extra 50 watts would be headroom you pay for and never hear.
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.