These are not the same size of amplifier: PS Audio PMG M800 has roughly 2.7x the power of Accuphase P-4600. That is about 4.3dB, so it is a question of room size and how hard your speakers are to drive, not of one being the better amplifier.
| Area | Better | Why |
|---|
| Power | B | PS Audio PMG M800 has more power - 400W against 150W into 8 ohms. That is about 4.3dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Room size | depends | We rate Accuphase P-4600 the better fit for desk or near-field listening, a small room and a mid-size room, and PS Audio PMG M800 for a very large room. Match the amplifier to the room you actually have, not the one you want. |
| Grip on hard loads | evenly matched | Both behave much the same into 4 ohms - output nearly doubles (300W and 800W). |
| Analogue inputs | A | Accuphase P-4600 takes more analogue sources - 2 against 1. |
| Amplifier class | depends | Accuphase P-4600 is Class A/B and PS Audio PMG M800 is Class A/AB. 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 $14,999 at list. |
| Watts per dollar | B | PS Audio PMG M800 is the cheaper watt - about $37 per watt against $93. 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 PS Audio PMG M800
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: PS Audio PMG M800 measures better, Accuphase P-4600 costs about 7% less. With most speakers in most rooms that gap is smaller in practice than it looks here. 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 - PS Audio PMG M800 has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 150 watts is already more than most people ever use, and the extra 250 watts would be headroom you pay for and never hear - we rate PS Audio PMG M800 poorly for near-field use for exactly that reason.
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.