Different price classes - Rega Aethos costs roughly 3.4x what Rotel A14 MKII does. Expect it to lead on paper; the question is whether you will hear the difference through the speakers you own.
| Area | Better | Why |
|---|
| Power | A | Rega Aethos has more power - 125W against 80W into 8 ohms. That is about 1.9dB, which is a small step in loudness but real headroom on peaks. |
| Built-in DAC | B | Rotel A14 MKII has a DAC on board; the other needs an external one, which is another box, another power lead and another purchase. |
| Phono stage | depends | Rotel A14 MKII has a built-in phono stage (MM) and Rega Aethos 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. |
| Price | B | Rotel A14 MKII costs less - $1,600 against $5,395 at list. |
| Watts per dollar | B | Rotel A14 MKII is the cheaper watt - about $20 per watt against $43. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Rega Aethos B Rotel A14 MKII
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?
Rotel A14 MKII has the edge on paper, though not by much. The rows marked "depends" are more likely to decide this than the score is. If you play records, Rotel A14 MKII saves you buying a phono stage; if you do not, ignore that row entirely. If you already own a DAC or a streamer, the built-in one is money you are paying twice for, and Rega Aethos 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.