These are not the same size of amplifier: Naim Uniti Star has roughly 2.8x the power of Pass Labs INT-25. That is about 4.5dB, 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 Star has more power - 70W against 25W into 8 ohms. That is about 4.5dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Room size | depends | We rate Pass Labs INT-25 the better fit for desk or near-field listening and a small room, and Naim Uniti Star 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 Star has a DAC on board; the other needs an external one, which is another box, another power lead and another purchase. |
| Analogue inputs | A | Pass Labs INT-25 takes more analogue sources - 3 against 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. |
| Amplifier class | depends | Pass Labs INT-25 is Class A and Naim Uniti Star 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 Star takes up about 28% less shelf area (1371cm² against 1906cm²), and it is 125mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | Naim Uniti Star costs less - $5,699 against $8,360 at list. |
| Watts per dollar | B | Naim Uniti Star is the cheaper watt - about $81 per watt against $334. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Pass Labs INT-25 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 Uniti Star is the easier recommendation: it leads on most of the measured areas and costs less. Take Pass Labs INT-25 if one of the "depends" rows above describes your system. 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 Star 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 45 watts would be headroom you pay for and never hear - we rate Naim Uniti Star poorly for near-field use for exactly that reason. 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.
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.