Installed this morning, replacing pair of M700. First impressions.Will wait to comment on sound but not sure what I am expecting to “hear” as Paul says it is so good you don’t hear it! Feed volume level from PMG preamp essentially same as with mono blocks. Out of rack top of heat sinks around 110 ˚F. Will report later on temp in rack (10" shelf spacing, leaving less than 2" of head room but open all around.
I will be waiting eagerly for your report - if I were to replace my M1200’s the S400 would be my choice. Thanks for posting this and keeping us updated!
I have the S400 (which runs even hotter) in a similar shelf and the shelf above gets barely warm.
I’ve been told that breakin is about 100 hours and mine is at 115. There were changes to the sound around 90 hours. Initially the bass was overly lean but filled out by 15 to 20 hours.
Somewhere that I can not now find, I recall Chris B. posted that while he expected the demand for the S400 to be greater, he might lean toward the S200 because of its higher class A output.
Will there actually be an audible difference between the M700s and the S200s?
[Hides]
I hope not!
Sorry, I meant S200
I recall the same, Chris implying the S200 is the sweet spot within the stereo line, implying compromises with the S400.
You know there is!!!
My S200 was delivered yesterday afternoon. Thanks to wheels on the box, it was fairly easy to roll it upstairs into the listening room. Speaking of the box, it’s good to see the thoughtful multi-layer design where the final layer unfolds on all sides making it easy to pick up and move the amp.
Connecting and listening to the amp will be the weekend’s priority.
Congrats to all so far who have purchased and integrated the new PMG amps into your set ups. Eagerly awaiting all user comments as they evolve and show what they can do. Especially interested in anyone that has transitioned from the BHK 250 to the S400 or S200. Your input is very much appreciated!
@JKWAustin - I like this setup. What are you using for speakers?
Here is a question. Regarding bass filling out after 15-20 hours, how is that not measurable? Maybe not a listener by ear, but by instrumentation that PS Audio certainly has.
A dangerous question! 
I love it.
I don’t know whether or not it is measurable with instrumentation since I don’t have any. But it was clearly audible (no intoxicants involved). I expect it was a new component breaking in even though some don’t believe in that.
Measurement phobia here. Waste of focus. Focus on the sound, forget the measurements.
Perhaps the most relevant datum for my listening experience with the S200 versus the M700 is that the latter are back in their factory box set to go via FedEx back to CO.
I am not equipped to do real time A/B testing so my SQ impressions suffer from the bugaboo of elapsed time between measurements. When the difference is dramatic, as it was with the change from Stellar gold to PMG 512, then sonic memory variability while still a factor can be less than the change. And, as I have previously noted in this forum, sonic memory is why I do not believe there is solid evidence for burn in (besides which there is no reason burn in should always result in an improvement).
After listening to to my favorite six or so albums (rated on both SQ and the music, I am happy with the change.
The effect of vertical confinement on unit temperature is less than 10 F and the effect on temperature on the upper surface of the overlying shelf is negligible but keep in mind my shelves are thick butcher block.
I am using the S200 to drive FR20’s. PMG preamp volume range 20-33 depending on music source and genre but I do live in an apartment with neighbors above and below through concrete floor and ceiling. Anyone know how to measure an amps output power level? Am curious as to where I am in the S200 power range.
I should have said before how I am using the S400. The system is biamped with the S400 on the bass of FR30s. I chose it over the S200 to have more power driving the bass. Of course I can’t say much about the upper frequencies but I do hear improvements into the midrange.
The S400 replaced a BHK 250 and for me it is a vast improvement. I knew the 250 was a little too bloomy in the bass but I was surprised at how much. The S400 is more clean and tuneful in the bass and goes lower into the deep bass with very good control there. There was also a cleanup in the midrange. I could better hear what the BHK 600s were doing in the upper frequencies and I would now rate them a notch or two higher than before.
However if I was using it full range I probably would have chosen the S200 with the higher class A power rating.
Have you ever had a fully burned in piece of audio equipment, in your home, and been able to listen to music through it for at least 3 weeks? And then swap it for a brand new same exact piece of equipment? I have. Burn in is most certainly real. Very, very real. You are trying to convince yourself of something by applying a theory instead of simply listening. Theories always get in the way and inflict a pre-determined bias. Don’t inflict a pre-determined bias either for or against burn in. Just listen to music.
Congrats on your new amp and the immediate improvement it made in your system. One day, maybe 2 weeks, maybe 1 or 2 months ftom now, you just might realize that the sound quality of music on your system actually got better. Just simply listen to music, and give it some time. At the audiophile level your system is at, you should be able to hear further into the music than ever before.