Both are Rega, from different ranges - the engineering approach is shared and the differences are mostly in power, connectivity and price.
| Area | Better | Why |
|---|
| Power | A | Rega Brio has more power - 50W against 30W into 8 ohms. That is about 2.2dB, 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 a very large room, and Rega io for desk or near-field listening. Match the amplifier to the room you actually have, not the one you want. |
| Analogue inputs | A | Rega Brio takes more analogue sources - 4 against 2. |
| Shelf space | depends | Rega io takes up about 30% less shelf area (522cm² against 745cm²), and it is 55mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | Rega io costs less - $725 against $1,100 at list. |
A Rega Brio B Rega io
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: Rega Brio measures better, Rega io costs about 34% 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 - Rega Brio has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 30 watts is already more than most people ever use, and the extra 20 watts would be headroom you pay for and never hear. Think about the whole system: the roughly $375 saved by taking the cheaper one would buy better speakers or a subwoofer, which does more for the sound than the difference between two competent amplifiers.
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.