These are not the same size of amplifier: Denon PMA-3000NE has roughly 2x the power of Naim Uniti Atom. 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 PMA-3000NE has more power - 80W against 40W into 8 ohms. That is about 3dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Built-in DAC | B | Both decode on board, but only Naim Uniti Atom handles DSD. |
| Streaming | evenly matched | Only Naim Uniti Atom has Roon. Neither list is longer in a way that matters - check the one service you actually pay for. |
| Phono stage | depends | Denon PMA-3000NE has a built-in phono stage and Naim Uniti Atom 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. |
| Shelf space | depends | Naim Uniti Atom takes up about 62% less shelf area (781cm² against 2066cm²), and it is 159mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | evenly matched | Priced within a few per cent of each other. |
| Watts per dollar | A | Denon PMA-3000NE is the cheaper watt - about $47 per watt against $95. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Denon PMA-3000NE B Naim Uniti Atom
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 PMA-3000NE has the edge on paper, though not by much. The rows marked "depends" are more likely to decide this than the score is. 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 PMA-3000NE has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 40 watts is already more than most people ever use, and the extra 40 watts would be headroom you pay for and never hear. If you play records, Denon PMA-3000NE 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.