Bass leaves after amp warms up?


I don't understand-after my Musical Fidelity M6i amp warms up for about an hour I notice the deep bass & kick drum aren't the same.
They sound less musical with loss of weight/depth.The notes are there but the moving of air have left.Sound is has much less impact and boreing.
I had the same problem with Bryston amp so there is no defect with amps nor with the rest of my equipment/
PSB Synchrony one speakers,AQ cables,Bryston CD Player.
My question has anyone heard similar & is there a plausable reason?
fishing716
It's too bad this thread ended on a sour note. These 10 pages are full of well intentioned good advice. So many concerned Agoners willing to do research such as checking specs, reading white papers and the like. With such a perplexing problem the OP had, there needed to be some comic relief thrown in.
Hopefully Fishing now has a system he can enjoy.
If it had a happy ending, that's good enough for me. Nobody had me in a choke hold forcing me to try to help.