97 s-10 radio doesn't work

I have a 97 s-10 that the radio quit working in. I tried a friends radio and it didn't work either. Then I tried my radio in his truck and it worked. Is there a amp or something else in line between the radio and the speakers? I also tried a different radio and fed the signal to each of the speakers but got no sound out. I hooked it up to a spare speaker I had layin around and it worked. Any ideas or info would be great,thanks

Are you getting power to it? Have you checked your fuses?