These are not the same size of amplifier: Cambridge Audio Evo 150 SE has roughly 3.8x the power of Naim Uniti Atom. That is about 5.7dB, 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 | A | Cambridge Audio Evo 150 SE has more power - 150W against 40W into 8 ohms. That is about 5.7dB - a different class of amplifier rather than a bigger version of the same one, and far more than most rooms will ever ask for. |
| Built-in DAC | evenly matched | Both have a DAC on board with much the same capability. |
| Streaming | evenly matched | Only Cambridge Audio Evo 150 SE has AirPlay 2. Neither list is longer in a way that matters - check the one service you actually pay for. |
| Phono stage | depends | Cambridge Audio Evo 150 SE has a built-in phono stage (MM) and Naim Uniti Atom does not. Decisive if you own a turntable, completely irrelevant if you do not - and an outboard phono stage is easy to add later either way. |
| Room to grow | evenly matched | The same expansion options on both. |
| Amplifier class | depends | Cambridge Audio Evo 150 SE is Class D and Naim Uniti Atom is Class A/B. Class D runs cool and draws almost nothing at idle; 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 Atom takes up about 34% less shelf area (781cm² against 1185cm²), and it is 56mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | A | Cambridge Audio Evo 150 SE costs less - $3,299 against $3,799 at list. |
| Watts per dollar | A | Cambridge Audio Evo 150 SE is the cheaper watt - about $22 per watt against $95. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Cambridge Audio Evo 150 SE B Naim Uniti Atom
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?
Cambridge Audio Evo 150 SE is the easier recommendation: it leads on most of the measured areas and costs less. Take Naim Uniti Atom 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 - Cambridge Audio Evo 150 SE has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 40 watts is already more than most people ever use, and the extra 110 watts would be headroom you pay for and never hear. If you play records, Cambridge Audio Evo 150 SE saves you buying a phono stage; if you do not, ignore that row entirely.
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.