One is a streaming all-in-one and the other is an amplifier. Judge them on how many boxes you want and what you already own, not on the spec sheet alone.
| Area | Better | Why |
|---|
| Power | A | Cambridge Audio Evo 150 SE has more power - 150W against 80W into 8 ohms. That is about 2.7dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Grip on hard loads | A | Cambridge Audio Evo 150 SE holds up better into a 4-ohm load: its output increases strongly to 250W, where the other increases strongly. That matters with demanding speakers far more than the 8-ohm figure does. |
| Built-in DAC | evenly matched | Both have a DAC on board with much the same capability. |
| Streaming | A | Only Cambridge Audio Evo 150 SE has AirPlay 2, Chromecast and Roon. |
| Phono stage | depends | Cambridge Audio Evo 150 SE has a built-in phono stage (MM) and Cambridge Audio CXA81 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 Cambridge Audio CXA81 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 | Cambridge Audio Evo 150 SE takes up about 26% less shelf area (1185cm² against 1595cm²). |
| Price | B | Cambridge Audio CXA81 costs less - $1,499 against $3,299 at list. |
A Cambridge Audio Evo 150 SE B Cambridge Audio CXA81
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 150 SE measures better, Cambridge Audio CXA81 costs about 55% less. With most speakers in most rooms that gap is smaller in practice than it looks here. If your speakers are a difficult load - 4 ohms nominal, big woofers, or a sensitivity in the low 80s - Cambridge Audio Evo 150 SE is the safer partner, because how an amplifier behaves when the impedance drops matters more than its 8-ohm rating. 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, 80 watts is already more than most people ever use, and the extra 70 watts would be headroom you pay for and never hear.
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.