How can i tell if my car stereo has blown channels?

In my 2001 sebring, I couldn't hear anything out of one rear speaker and the other one sounds crappy. I hooked up another speaker to them and it does the same thing so i know it's not the speakers. I have the stereo pulled out and there are two clips with 5 wires in each so how do i tell if it's the channels blown or possibly cut wiring somewhere in the car.How can i tell if my car stereo has blown channels?
If one of the channel is blown then you are not going to hear anything from that channel. Factory head units are not very good anyway. Hope this will help you out.