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 | A | Mark Levinson No.585.5 has more power - 200W against 150W into 8 ohms. That is about 1.2dB, which is a small step in loudness but real headroom on peaks. |
| Room size | depends | We rate Mark Levinson No.585.5 the better fit for a very large room, and Devialet Astra for desk or near-field listening, a small room and a mid-size room. Match the amplifier to the room you actually have, not the one you want. |
| Grip on hard loads | B | Devialet Astra holds up better into a 4-ohm load: its output nearly doubles to 300W, where the other increases strongly. That matters with demanding speakers far more than the 8-ohm figure does. |
| Bass control | B | Devialet Astra has the higher damping factor (2000 vs 400), 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 | Both decode on board. Devialet Astra goes higher - 384kHz against 192kHz. Very few recordings exist above 192kHz, so treat this as headroom, not as sound quality. |
| Analogue inputs | A | Mark Levinson No.585.5 takes more analogue sources - 4 against 2. |
| Room to grow | evenly matched | The same expansion options on both. |
| Amplifier class | depends | Mark Levinson No.585.5 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 | Mark Levinson No.585.5 costs less - $16,575 against $20,000 at list. |
| Watts per dollar | A | Mark Levinson No.585.5 is the cheaper watt - about $83 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 Mark Levinson No.585.5 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?
Neither runs away with it - they trade advantages. Let the "depends" rows and the speakers you already own settle it. If your speakers are a difficult load - 4 ohms nominal, big woofers, or a sensitivity in the low 80s - Devialet Astra is the safer partner, because how an amplifier behaves when the impedance drops matters more than its 8-ohm rating.
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.