Bass leaves after amp warms up?

Fish . . . I looked the dealer up on the internet. It appears he carries Bryston. If a Bryston amp can't drive those speakers, nothing can. I like the idea of trying an extremely robust amp like a Bryston.

But do check out Zero the autoformer web site. As I said, I seem to recall, if not satisfied, I think the guy will take the Zeros back and issue a refund. If nothing else, check out the web site to understand what Zeros do. In short, they are an impedance multiplier. Simply stated, under one setting, the Zeros can make your amp think its driving twice the impedance load than it really is, i.e., nominal 4 ohms x 2 equals 8 ohms. Your amp will take a vacation with shades. ;>)

I had 2 Bryston integrated amps before switching to MF

I hear the "correct sounding bass like blood flowing through the music..My feet are toe taping & I am never figidigy..
After between 1 hr & 3 the sound changes and the patient no longer has the same "blood type"..
My toe no longer taps and it's not worth listening any more.So I would say the difference is like night & day.

Today after the desired sound left I waited a few hrs but it didn't return.

I pulled out the speaker cables on one side of the amp and reconnected the other side in it's place.
After 3 tries back and forth the bass returned in full bloom with one speaker connected.
I settle with this as I don't wish to risk blowing the found sound trying to have both speakers working.
But a major clue seems to be that I can usually find a way to get one speaker working with deep bass after losing the sound from one or both.
For some reason when the amp peaks after an hr.or so there is a distruption or short somewhere.
Like the amp or speakers need to reboot
I resent having to go though this nonsence daily

No way! Are the Bryston integrateds as muscular as a separate Bryston power amps. Call the factory and ask the techs. I can't go back to read all the steps taken to isolate the problem, but I assume working backwards you eliminated your source components (i.e., CDP and phono, as applicable), cables, etc.

If so, that could mean, as has been surmised above, the "true" impedance of your speakers may be lower than the nominal 4 ohms I seem to recall being mentioned. Actual versus "nominal" reported impedance stats can vary quite significantly and often do. Very few amps "like" driving into those kinds of loads. If a monster Bryston doesn't work, I think you go back to "Zeros" and see if that helps.

Btw, just an "fyi" I picked up some time ago when talking to Kal at ARC. He mentioned that ARC tube amps were used to drive Wilsons which have notoriously low impedance stats. Just an fyi.

Otherwise, as Al says, you have to consider the only remaining possibility, no matter how improbable: Poltergeists.

I'm going to see if your PSB speakers were bench tested by any of the reviewers. If so, I'll be back.

I asked mike at Bryston when considering Preamp BP17 & power amp 2.5BSST
He said they were the same as B135sst integrated in seperate boxes