Car Stereos: problems with my stereo, stock radio, pontiac g6

Question
i have an '08 pontiac g6. one day everything quit working other than the highs. i got two 12 in. sub speakers and an amp istalled a while ago. best buy guy says i need a new stock amp and that it doesnt relate to anything they did. the dealership won't count it under my warranty cause they believe the problem could be caused by me adding to it. but i didnt take the stock radio out or mess with anything?? so is it just a bad stock amp??

Answer
It may be a bad stock amplifier, but you want to be sure that the aftermarket wiring is not shorting out between where they spliced into the rear speakers wires to where they get to the sub amp.  If there is a short in that wire, then the installation did cause the bad stock amp.  If there is no shorts between the splice and the sub amp, then the problem is solely in the factory amp.  Either way, you want to double check all wires going to and coming from stock amp for shorts before replacing amplifier.  Hope this helps, Scott