Different price classes - Naim Uniti Nova costs roughly 3x what Naim Nait 5si does. Expect it to lead on paper; the question is whether you will hear the difference through the speakers you own.
| Area | Better | Why |
|---|
| Power | B | Naim Uniti Nova has more power - 80W against 60W into 8 ohms. That is about 1.2dB, which is a small step in loudness but real headroom on peaks. |
| Room size | depends | We rate Naim Nait 5si the better fit for desk or near-field listening and a small room, and Naim Uniti Nova 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 | 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 | Naim Nait 5si takes more analogue sources - 4 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 | A | Naim Nait 5si costs less - $2,299 against $6,899 at list. |
| Watts per dollar | A | Naim Nait 5si is the cheaper watt - about $38 per watt against $86. 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 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 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.