Both are Naim, from different ranges - the engineering approach is shared and the differences are mostly in power, connectivity and price.
| Area | Better | Why |
|---|
| Power | A | Naim NAP 250 has more power - 100W against 70W into 8 ohms. That is about 1.5dB, which is a small step in loudness but real headroom on peaks. |
| Speaker load rating | A | Naim NAP 250 is rated down to 2 ohms against 4, so it is the safer partner for a low-impedance speaker. |
| Built-in DAC | B | Naim Uniti Star has a DAC on board; the other needs an external one, which is another box, another power lead and another purchase. |
| Analogue inputs | evenly matched | The same number of line-level inputs (1). |
| Use with a TV | depends | Only Naim Uniti Star 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. |
| Headphones | depends | Only Naim Uniti Star has a headphone output. Worth something if you listen late, nothing if you never do. |
| Built-in sources | depends | Naim Uniti Star has a CD player built in. That is one less box if you still play discs or listen to radio, and dead weight if you do not. |
| Price | B | Naim Uniti Star costs less - $5,699 against $8,999 at list. |
A Naim NAP 250 B Naim Uniti Star
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?
Naim NAP 250 is ahead, but on only 1 of the measured areas, and it costs about 58% more. That is a lot of money for a narrow margin - Naim Uniti Star is the sensible buy unless a specific feature above decides it for you. If this sits under a television, Naim Uniti Star 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 NAP 250 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.