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
"This thread as a whole is a great example of audiophiles and audiophile forums at their best. A very special thread indeed. "

You mean as an example of how audiophiles tend to obsess on fixing their sound based on limited facts and thus spend vast amounts of time and money in the process? :^)
"The spirit of assistance was strong in this thread."

Oh, yeah, that too!

Luckily, the force was with us I suppose....
"The spirit of assistance was strong in this thread."

But why didn't it end a long time ago?