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 - 90W against 80W into 8 ohms is under 1dB, which is not an audible difference in loudness. |
| Built-in DAC | B | Naim Uniti Nova has a DAC on board; the other needs an external one, which is another box, another power lead and another purchase. |
| Analogue inputs | A | Accuphase E-280 takes more analogue sources - 5 against 2. |
| Use with a TV | depends | Only Naim Uniti Nova has HDMI ARC, so the television can drive it directly and one remote controls the volume. If the system is for music only, this changes nothing. |
| Price | evenly matched | Priced within a few per cent of each other. |
A Accuphase E-280 B Naim Uniti Nova
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. If this sits under a television, Naim Uniti Nova is the one to buy - HDMI ARC means the TV remote controls the volume and there is no second box in the way. If you already own a DAC or a streamer, the built-in one is money you are paying twice for, and Accuphase E-280 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.