Different price classes - PS Audio BHK Mono 600 costs roughly 4.3x what PS Audio Stellar M1200 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 | evenly matched | Effectively the same output - 600W against 600W into 8 ohms is under 1dB, which is not an audible difference in loudness. |
| Noise floor | B | PS Audio Stellar M1200 is the quieter design on paper - 112dB against 100dB. Audible mainly with sensitive speakers in a quiet room. |
| Analogue inputs | evenly matched | The same number of line-level inputs (1). |
| Amplifier class | depends | PS Audio BHK Mono 600 is Class A/B and PS Audio Stellar M1200 is Class D. Class A/B runs warm and is the long-established mainstream choice; Class D runs cool and draws almost nothing at idle. Modern examples of both measure well - judge by the rest of the page. |
| Shelf space | depends | PS Audio Stellar M1200 takes up about 15% less shelf area (1316cm² against 1544cm²), and it is 51mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | PS Audio Stellar M1200 costs less - $3,499 against $14,999 at list. |
| Watts per dollar | B | PS Audio Stellar M1200 is the cheaper watt - about $6 per watt against $25. 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 PS Audio Stellar M1200
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?
PS Audio Stellar M1200 is the easier recommendation: it leads on most of the measured areas and costs less. Take PS Audio BHK Mono 600 if one of the "depends" rows above describes your system. Think about the whole system: the roughly $11,500 saved by taking the cheaper one would buy better speakers or a subwoofer, which does more for the sound than the difference between two competent amplifiers.
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.