I have read the threads but didn't find an answer. 94 SHO ATX JBL sound system, everything seems to work, tape, CD, radio except there is no sound at all from any of them. I have checked the connections on the back of all the units and they seem fine, the connections to the amps in the trunk also seem fine. Any way to test the units and amps or do I have to go to a sound shop? Also the fuse was inspected and is good. All advice is appreciated.