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 | evenly matched | Effectively the same output - 60W against 70W into 8 ohms is under 1dB, which is not an audible difference in loudness. |
| Room size | depends | We rate Naim Nait 5si the better fit for desk or near-field listening and a small room, and Denon PMA-1700NE for a mid-size room, a large room and a very large room. Match the amplifier to the room you actually have, not the one you want. |
| Built-in DAC | B | Denon PMA-1700NE has a DAC on board; the other needs an external one, which is another box, another power lead and another purchase. |
| Analogue inputs | A | Naim Nait 5si takes more analogue sources - 4 against 3. |
| Phono stage | depends | Denon PMA-1700NE has a built-in phono stage (MM,MC) and Naim Nait 5si 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. |
| Shelf space | depends | Naim Nait 5si takes up about 33% less shelf area (1300cm² against 1949cm²), and it is 147mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | Denon PMA-1700NE costs less - $2,099 against $2,299 at list. |
| Watts per dollar | B | Denon PMA-1700NE is the cheaper watt - about $30 per watt against $38. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Naim Nait 5si B Denon PMA-1700NE
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-1700NE has the edge on paper, though not by much. The rows marked "depends" are more likely to decide this than the score is. If you play records, Denon PMA-1700NE saves you buying a phono stage; if you do not, ignore that row entirely. If you already own a DAC or a streamer, the built-in one is money you are paying twice for, and Naim Nait 5si becomes the more rational buy.
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.