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
The OP isn't willing to try much.

SPL meter? Nope. He's a professional musician, won't try the SPL meter. Taking the cover off the amp? Nope, no tool. Unwilling to go to the store to buy a set of allen keys. Besides, he isn't good at taking the cover off, he has the dexterity to be a musician but he can't turn a screw.

(Hardware stores will have both US and metric sizes by the way -- really easy investment.)

Likes swapping speaker cables though.

There's 148 posts to this thread and I haven't read them all but I know that's it's been brought up. I just don't know what your response was.

Why don't you at least try a power regenerator like a PS Audio unit to rule out any chance that it's a power problem from high usage? That way you know that your power to all of your components is consistent.

Chuck
When someone reports that bass disappears after some time, it really could be something somewhat different--it could be that the midrange or highs have gotten stronger rather than the bass getting weaker. It is not absolute level that matters so much as the balance.

Again, I will theorize that after the system has warmed up, the tonal balance has changed and the original poster may simply not like the tonal balance of his system in a warmed up state.
Larryi, You just duplicated my post from the beginning of this thread and after 150 posts I still believe this is the OP's problem. Tonal balance is a delicate thing and it doesn't take much to throw the sound off.