Two versions of the same amplifier rather than two different designs, so the question is not which is better built but which set of features you actually need - and what the difference costs.
| Area | Better | Why |
|---|
| Power | evenly matched | Effectively the same output - 50W against 50W into 8 ohms is under 1dB, which is not an audible difference in loudness. |
| Built-in DAC | B | Rega Brio Mk 7 has a DAC on board; the other needs an external one, which is another box, another power lead and another purchase. |
| Analogue inputs | evenly matched | The same number of line-level inputs (4). |
| Price | A | Rega Brio costs less - $1,100 against $1,195 at list. |
A Rega Brio B Rega Brio Mk 7
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 Mk 7 measures better, Rega Brio costs about 8% less. With most speakers in most rooms that gap is smaller in practice than it looks here. If you already own a DAC or a streamer, the built-in one is money you are paying twice for, and Rega Brio becomes the more rational buy.
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.