Bass leaves after amp warms up?

If you had the same problem with the Bryston amp it's very unlikely a power amp issue. Sounds like a power issue. Either line/conditioner or pc. Have you tried switching power cords? Maybe a defective conditioner? Voltage flucuation?

Simply would like to know if anyone has experiencd even a noticable change of music being reproduced from one time to another?
It seems the symptoms I hear have no precident..
Which bothers me the most I think
I've looked on line + spoken to all the manfacutures of my equipment..Most won't even accept my calls any longer.

" I never ever listen to music loud"

Good to know. Its probably not the amp then.

Have you tried different speakers, as Kijanki thought you might have? And if so, did the same phenomenon occur with them?

I'm still suspicious of the possibility that the performance of your speakers is changing after they have been playing music for the hour.

Regards,
-- Al

I have seen cases where old switches in pre-amps or other gear cause a very significant loss of power over time as they oxidize, etc., and good contacts are lost. Same true with volume controls, balance controls, etc.

If there are any manual switches in play with your gear, next time you hear it, try twidling with controls and switches and listen for any differences. THe twidlling alone might help but if so a good cleaning is probably in order.

This happens with my old NAD 7020 receiver from 30 years ago that I still use. A few twiddles with the input switch on occasion when I notice things have faded out sets things right again until thenext cleaning of switches and controls. Not an uncommon thing...