Different price classes - Rega Aethos costs roughly 2.6x what Denon PMA-1700NE 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 70W into 8 ohms. That is about 2.5dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Built-in DAC | B | Denon PMA-1700NE has a DAC on board; the other needs an external one, which is another box, another power lead and another purchase. |
| Phono stage | depends | Denon PMA-1700NE has a built-in phono stage (MM,MC) 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 | Denon PMA-1700NE costs less - $2,099 against $5,395 at list. |
| Watts per dollar | B | Denon PMA-1700NE is the cheaper watt - about $30 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 Denon PMA-1700NE
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?
Denon PMA-1700NE has the edge on paper, though not by much. The rows marked "depends" are more likely to decide this than the score is. 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 Aethos has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 70 watts is already more than most people ever use, and the extra 55 watts would be headroom you pay for and never hear. If you play records, Denon PMA-1700NE 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.