A valve amplifier against a solid-state one. They are not really rivals: they differ in character, in what they will drive and in what owning them involves, so start there rather than with the watts.
| Area | Better | Why |
|---|
| Power | A | PS Audio BHK Mono 600 has more power - 600W against 150W into 8 ohms. That is about 6dB - a different class of amplifier rather than a bigger version of the same one, and far more than most rooms will ever ask for. |
| Room size | depends | We rate PS Audio BHK Mono 600 the better fit for a very large room, and Accuphase P-4600 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. |
| Analogue inputs | B | Accuphase P-4600 takes more analogue sources - 2 against 1. |
| Amplifier type | depends | PS Audio BHK Mono 600 is Hybrid and Accuphase P-4600 is Solid State. Valve designs are usually warmer and softer at the limits and need their tubes replaced eventually; solid state is the lower-maintenance choice. This is a taste and ownership decision, not a quality one. |
| Price | B | Accuphase P-4600 costs less - $13,975 against $14,999 at list. |
| Watts per dollar | A | PS Audio BHK Mono 600 is the cheaper watt - about $25 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 PS Audio BHK Mono 600 B Accuphase P-4600
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 BHK Mono 600 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 BHK Mono 600 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 450 watts would be headroom you pay for and never hear - we rate PS Audio BHK Mono 600 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.