These are not the same size of amplifier: Cambridge Audio Evo 300 has roughly 7.5x the power of Naim Uniti Atom. That is about 8.8dB, 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 300 has more power - 300W against 40W into 8 ohms. That is about 8.8dB - 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 | A | Both decode on board. Cambridge Audio Evo 300 goes higher - 768kHz against 384kHz. Very few recordings exist above 192kHz, so treat this as headroom, not as sound quality. |
| Streaming | evenly matched | Only Cambridge Audio Evo 300 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 300 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 300 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 47% less shelf area (781cm² against 1463cm²), and it is 60mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | Naim Uniti Atom costs less - $3,799 against $3,999 at list. |
| Watts per dollar | A | Cambridge Audio Evo 300 is the cheaper watt - about $13 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 300 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 300 leads across most of the measured areas for a fairly modest premium, so it is the easier pick if the budget stretches. Naim Uniti Atom 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 - Cambridge Audio Evo 300 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 260 watts would be headroom you pay for and never hear. If you play records, Cambridge Audio Evo 300 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.