Bass leaves after amp warms up?

After the sound drops out I leave the amp on w/o music playing.
I Return after an hr.or the next morning
Generaly the sound has improved by then-
For another brief listening session

I suspect quantitative analysis of recordings of the system will be inconclusive at best do to difficulty of assuring all parameters that went into the recording. But ya never know...

I'm willing to bet the new MF amp will do much better. IF dynamics and bass is what OP is missing when listening, as best I can tell that amp should do it from what I read, and I would expect OP to hear better results in those regards and overall.

Although specs or bench measurements into 4 ohms would be re-assuring, advertised current delivery capability and verbal claim in MF literature to be able to drive more challenging speaker loads sounds promising.

I had MF A3CR amp prior to current BEl Canto Ref1000ms. They seemed up to the task of handling my larger more difficult load speakers, OHM 5 series 3s. These are a challenge but possibly not as much so as the OPs PSBs from what I read. THe OPs new trial amps would appear to be significantly beefier than the A3CR on paper in regards to both power output and current delivery, a good omen.

We'll see....

Hello AL:
I re-recorded the two versions of "Respect youself" with the proper adjustments.
What is your email,I will send them to you.
Or anyone else that would like to hear good/bad bass versions(as they sound to me).
tonypoid@aol.com

Fishing, Have you tried putting a fan on the amplifier?

Based on all that we have discussed, it does seem that heat plays a huge role. The fan should be able to cool the amp's heatsinks.

Or even just with the top cover off. Better yet, two sets of recordings should be done; with and without added cooling. This could end up being a very fruitful case study on due diligence by ss amp manufacturers. No wonder there's separate tube and ss camps. Tubes and mosfets do after all share some similarities.