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
Fishing, I still find myself uncertain of the meaning of your description of the connections. I think you are saying (correct me if I'm wrong) that what you WERE doing was:

1)Connecting the "red treble" banana plug of the cable to the red binding post of the high frequency part of the speaker.

2)Connecting the "black treble" banana plug of the cable to the black binding post of the low frequency part of the speaker.

3)Connecting the "red bass" banana plug of the cable to the red binding post of the low frequency part of the speaker.

4)Connecting the "black bass" banana plug of the cable to the black binding post of the high frequency part of the speaker.

In other words, you were interchanging the connections of the two black banana plugs at the speaker end of the cable.

If that is correct, like Dan (Drubin) I don't see how that would cause the bass to be fine for an hour or so, and then mostly disappear. JJ offered a clever theory, but looking at the description and photos of the Comet at the AQ site I don't see anything suggesting that the gauge of the treble wiring is extremely thin, which it would have to be for a resistance rise due to heating to become significant.

Regards,
-- Al
If speakers were connected out of phase, bass would be impacted from the get go, not more so over time. That could have just been a perception that it got worse over time. Whatever. If it sounds good now, take a note on how to wire correctly so you can do it again if needed. Reds to + and blacks to - in all connections from amp and into speakers should do it!
ALso note that there is no reason to biwire from a single amp to multiple speaker connections for biwiring. It may work fine if done right but more chance for error. Just make sure jumper on speakers between reds/+s and other jumper between blacks/-s is in place and conect to speakers in phase properly just once.
JJ offered a clever theory, but looking at the description and photos of the Comet at the AQ site I don't see anything suggesting that the gauge of the treble wiring is extremely thin,

Don't know how clever it was but after 454 posts from lots of experts I can only come up with what are obviously long "reachs" for a possible explanation for the bass issue. I agree with Al that the wire that "biased towards high frequency finesse" does not look thin enough to be a problem however I am not well versed in the AQ wire topology or how the battery bias may be working if hooked up wrong. Also I came to the same conclusion, now that I know the cable, is that the only miswire that should still work should effect the bass from the start, not change with playing time.

Also there has been some discussion of the PSB's having a low impedance. I have not seen a graph but if that dip is in the bass range it would, IIUC, not take to much of an increase in wire resistance to effect the damping factor. IMO, from the recordings that were sent out, it is not a quantity of bass issue it is the quality of the bass that changes.

Again, a way out theory, but without physically seeing the internal construction of the speaker wire it's all I got at the moment.