Different price classes - PS Audio PMG M800 costs roughly 8.6x what PS Audio Stellar M700 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 - 400W against 350W 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 (800W and 700W). |
| Analogue inputs | evenly matched | The same number of line-level inputs (1). |
| Amplifier class | depends | PS Audio PMG M800 is Class A/AB and PS Audio Stellar M700 is Class D. 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 M700 takes up about 56% less shelf area (1316cm² against 3020cm²), and it is 375mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | PS Audio Stellar M700 costs less - $1,749 against $14,999 at list. |
| Watts per dollar | B | PS Audio Stellar M700 is the cheaper watt - about $5 per watt against $37. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A PS Audio PMG M800 B PS Audio Stellar M700
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 M700 has the edge on paper, though not by much. The rows marked "depends" are more likely to decide this than the score is. Think about the whole system: the roughly $13,250 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.