Help with distorsion on start up of home theater

Hey all , it seems when i turn on my yamaha reciever and power up my bryston amp I get a distorted sound. If I turn on one before the other it does not make a difference. And if I play the distorted sound through the speakers it warms up and after about 25min it finally comes around. The distorted sound is very audible , it sounds like a dirty volume nob with the music cutting in and out. Does any one know what gives here. I also unhooked the bryston and the interior amps seem to play fine. I also hooked up the bryston to another preamp of a friends and it seemed OK.

If anyone knows anything I would appreciate some thoughts on the matter. Thanks in advance.