bose 6 disc stereo no sound on 2004 GMC Sierra 3500

Ive got no sound, no door chimes ,no phone or onstar not working the radio seems to function other than no sound.the fuses have been checked ok and it has power running to the stereo. is there a pre amp and where do I find it.

Asked by for the 2004 GMC Sierra 3500
suggest that you look for a local auto radio repair shop.
if the preamp is problem, many times they can fix it instead of replacing it.