Siblings in Naim's NAP range, so they share a design and a house sound. It comes down to power, features and price.
| Area | Better | Why |
|---|
| Power | A | Naim NAP 350 has more power - 175W against 100W into 8 ohms. That is about 2.4dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Room size | depends | We rate Naim NAP 350 the better fit for a large room and a very large room, and Naim NAP 250 for desk or near-field listening, a small room and a mid-size room. Match the amplifier to the room you actually have, not the one you want. |
| Grip on hard loads | evenly matched | Both behave much the same into 4 ohms - output nearly doubles (345W and 190W). |
| Bass control | evenly matched | Similar damping factor (36 vs 36). |
| Analogue inputs | evenly matched | The same number of line-level inputs (1). |
| Price | A | Naim NAP 350 costs less - $8,499 against $8,999 at list. |
| Watts per dollar | A | Naim NAP 350 is the cheaper watt - about $49 per watt against $90. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Naim NAP 350 B Naim NAP 250
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 350 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 - Naim NAP 350 has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 100 watts is already more than most people ever use, and the extra 75 watts would be headroom you pay for and never hear - we rate Naim NAP 350 poorly for near-field use for exactly that reason.
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.