One is a streaming all-in-one and the other is an amplifier. Judge them on how many boxes you want and what you already own, not on the spec sheet alone.
| Area | Better | Why |
|---|
| Power | evenly matched | Effectively the same output - 60W against 50W into 8 ohms is under 1dB, which is not an audible difference in loudness. |
| Noise floor | B | Denon PMA-900HNE is the quieter design on paper - 105dB against 100dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | B | Both decode on board, but only Denon PMA-900HNE handles DSD. |
| Streaming | B | Only Denon PMA-900HNE has AirPlay 2, Roon and HEOS. |
| Analogue inputs | A | Rotel A12 takes more analogue sources - 4 against 3. |
| Room to grow | evenly matched | The same expansion options on both. |
| Price | A | Rotel A12 costs less - $800 against $949 at list. |
| Watts per dollar | A | Rotel A12 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 Rotel A12 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?
The usual trade-off: Denon PMA-900HNE measures better, Rotel A12 costs about 16% less. With most speakers in most rooms that gap is smaller in practice than it looks here.
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.