No single best amplifier here. What decides it is what you have to drive, what you need to plug in, and how much of the system you want in one box.
| Area | Better | Why |
|---|
| Power | evenly matched | Effectively the same output - 150W against 150W into 8 ohms is under 1dB, which is not an audible difference in loudness. |
| Grip on hard loads | evenly matched | Both behave much the same into 4 ohms - output nearly doubles (300W and 300W). |
| Bass control | B | Devialet Astra has the higher damping factor (2000 vs 800), which usually means a tighter grip on a woofer. Above about 100 the returns flatten out, so read this as a tendency rather than a ranking. |
| Built-in DAC | B | Devialet Astra 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 (2). |
| Phono stage | depends | Devialet Astra has a built-in phono stage (MM/MC with 13 equalization curves and adjustable cartridge loading) and Accuphase P-4600 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. |
| Amplifier class | depends | Accuphase P-4600 is Class A/B and Devialet Astra is ADH (Analog Digital Hybrid). Class A/B runs warm and is the long-established mainstream choice. Modern examples of both measure well - judge by the rest of the page. |
| Price | A | Accuphase P-4600 costs less - $13,975 against $20,000 at list. |
| Watts per dollar | A | Accuphase P-4600 is the cheaper watt - about $93 per watt against $133. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Accuphase P-4600 B Devialet Astra
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?
Devialet Astra is ahead, but on only 1 of the measured areas, and it costs about 43% more. That is a lot of money for a narrow margin - Accuphase P-4600 is the sensible buy unless a specific feature above decides it for you. If you play records, Devialet Astra 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 Accuphase P-4600 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.