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
While I hope that the new amp fixes the issue, I'm skeptical. I recently read in another thread a post by I think Audiokinesis that describes situations in speakers where the voice coil gets too hot and starts to limit the bass response of a speaker. When reading that, I instantly thought of this thread. If that's the case, then it's the speakers, not the amps that are causing the issue.

Fishing, let us know how things progress.
The AA Power 1 mk.3 integrated is 200 watts into 8ohms
I paid $5000 new w/phono from distriubuter for a show demo open box.
I have 15 day test drive w/return option & no restock.
Although shipping both ways using fedex air w/insurance would be around $400
I chose this amp over Musical Fidelity pre/prx also Modwright KWI 200 & yamaha s2000
The amp arrives Wednesday-
I will post first impressions soon after
Fishing, definitely appears to be a very high quality integrated and I do hope this new amp works well for you, however someone has misinformed you about the power. The ratings I quoted was from the company's website.

http://www.accusticarts.com/pdf/produktblatt/power-I-mk3.pdf

Agree with Mapman, what's on paper never tells the whole story.