These are not the same size of amplifier: Naim Uniti Nova has roughly 3.2x the power of Pass Labs XA25. That is about 5.1dB, so it is a question of room size and how hard your speakers are to drive, not of one being the better amplifier.
| Area | Better | Why |
|---|
| Power | B | Naim Uniti Nova has more power - 80W against 25W into 8 ohms. That is about 5.1dB - a different class of amplifier rather than a bigger version of the same one, and far more than most rooms will ever ask for. |
| Room size | depends | We rate Pass Labs XA25 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 | evenly matched | The same number of line-level inputs (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. |
| Headphones | depends | Only Naim Uniti Nova has a headphone output. Worth something if you listen late, nothing if you never do. |
| Amplifier class | depends | Pass Labs XA25 is Class A and Naim Uniti Nova is Class A/B. Class A runs hot and is inefficient by design, in exchange for the simplest signal path; Class A/B runs warm and is the long-established mainstream choice. Modern examples of both measure well - judge by the rest of the page. |
| Shelf space | depends | Naim Uniti Nova takes up about 28% less shelf area (1371cm² against 1892cm²), and it is 122mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | A | Pass Labs XA25 costs less - $5,665 against $6,899 at list. |
| Watts per dollar | B | Naim Uniti Nova is the cheaper watt - about $86 per watt against $227. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Pass Labs XA25 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?
Naim Uniti Nova leads across most of the measured areas for a fairly modest premium, so it is the easier pick if the budget stretches. Pass Labs XA25 is the one to take if it does not. 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 Uniti Nova has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 25 watts is already more than most people ever use, and the extra 55 watts would be headroom you pay for and never hear - we rate Naim Uniti Nova poorly for near-field use for exactly that reason. 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.
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.