Bass leaves after amp warms up?

If everything has been swapped out and the one constant still in the system is the speakers ? Then i would be willing to wager it is the speakers ! No ?

Bass returned after waiting 30 minutes.
After about 30 minutes of sounding good it disappated.
Surely something causes deep bass to come & go as it wishes.
I have(3)ideas to try this week:
Electrician is going to check connections
I am borrowing different speaker cables
May put up $1745(demo)& try ps audio p-3 power conditioner with return previlage.

Yes. If I'm not mistaken, the PS Audio P-3 connects one lead to the right temple and the other to the left. Be very careful in plugging in the ground:)

Should I ask where you plug in the ground?

I will preface my comments by saying I have not read everything said above, so I may be covering ground that has been rehashed to death. If the problem persists after certain components have been switched out, it lies with those that have not been switched out. If it happens with different sources, it is probably not the source components. If it happens with different sources, or when a source has been switched out, or with different components in the amplification chain, that really leaves the speakers to be suspect. If one overheats speakers the sound does change dramatically. If, for example the woofer voice coil gets too hot, resistance will shoot up and the speaker will sound lighter in bass. The crossover components can also heat up and this will affect the sound dramatically as well-component values will shift and change crossover points, filter characteristics, etc. and could lead to the loss of bass.

Such obvious change in sonic characteristics, if due to overheating of the speaker, constitutes pretty rough treatment of the speakers. Perhaps something designed to produce higher volume is needed for this particular application.