JC, same exact thing here! Dealer wants $1200. to replace amp. Did you get yours fixed?
I am having a similar problem, Lexus did diagnostics and said I need to pay over a thousand dollars to have the Amp replaced.. I had the amp sent off and they said my amp hooked up to another car works fine. The place also sent back and working amp which has a similar problem in my car.. I have been told to check the wiring and the fuses.. thats next on the list..