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 | B | Cambridge CXA81 II has more power - 80W against 50W into 8 ohms. That is about 2dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Room size | depends | We rate Rega Brio the better fit for desk or near-field listening and a small room, and Cambridge CXA81 II 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 | Cambridge CXA81 II has a DAC on board; the other needs an external one, which is another box, another power lead and another purchase. |
| Streaming | evenly matched | Only Cambridge CXA81 II has Roon. Neither list is longer in a way that matters - check the one service you actually pay for. |
| Analogue inputs | B | Cambridge CXA81 II takes more analogue sources - 5 against 4. |
| Phono stage | depends | Rega Brio has a built-in phono stage (MM) and Cambridge CXA81 II 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 | B | Only Cambridge CXA81 II offers preamp outputs and a subwoofer output - which decides whether you can add a subwoofer or a power amplifier later without replacing the box. |
| Shelf space | depends | Rega Brio takes up about 53% less shelf area (745cm² against 1595cm²), and it is 25mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | A | Rega Brio costs less - $1,100 against $1,199 at list. |
| Watts per dollar | B | Cambridge CXA81 II is the cheaper watt - about $15 per watt against $22. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Rega Brio B Cambridge CXA81 II
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 CXA81 II leads across most of the measured areas for a fairly modest premium, so it is the easier pick if the budget stretches. Rega Brio 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 CXA81 II has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 50 watts is already more than most people ever use, and the extra 30 watts would be headroom you pay for and never hear - we rate Cambridge CXA81 II poorly for near-field use for exactly that reason. If you play records, Rega Brio 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.