These are not the same size of amplifier: Cambridge Audio Evo 300 has roughly 12x the power of Cambridge Audio AXA25. That is about 10.8dB, 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 25W into 8 ohms. That is about 10.8dB - a different class of amplifier rather than a bigger version of the same one, and far more than most rooms will ever ask for. |
| Speaker load rating | A | Cambridge Audio Evo 300 is rated down to 4 ohms against 8, so it is the safer partner for a low-impedance speaker. |
| Built-in DAC | A | Cambridge Audio Evo 300 has a DAC on board; the other needs an external one, which is another box, another power lead and another purchase. |
| Streaming | A | Only Cambridge Audio Evo 300 has AirPlay 2, Chromecast and Roon. |
| Phono stage | depends | Cambridge Audio Evo 300 has a built-in phono stage (MM) and Cambridge Audio AXA25 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 | A | Only Cambridge Audio Evo 300 offers preamp outputs - which decides whether you can add a subwoofer or a power amplifier later without replacing the box. |
| Headphones | depends | Only Cambridge Audio Evo 300 has a headphone output. Worth something if you listen late, nothing if you never do. |
| Amplifier class | depends | Cambridge Audio Evo 300 is Class D and Cambridge Audio AXA25 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. |
| Price | B | Cambridge Audio AXA25 costs less - $299 against $3,999 at list. |
A Cambridge Audio Evo 300 B Cambridge Audio AXA25
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?
The usual trade-off: Cambridge Audio Evo 300 measures better, Cambridge Audio AXA25 costs about 93% less. With most speakers in most rooms that gap is smaller in practice than it looks here. 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, 25 watts is already more than most people ever use, and the extra 275 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.