Audio Systems: New System, Old Car- No sound coming out of the speakers, chrysler newport, blaupunkt

Question
I have a 1966 Chrysler Newport, and I put in a system a couple of years ago.  It was working great until recently. I hadn't started it in a while and I had to replace the battery, starter and both neg and pos cables.  When I went to turn it on the head unit came on but no sound from the speakers.  It is a Blaupunkt Malibu Cd unit with a disk changer.  It has an amp and 12" sub in the trunk.  Could there be a grounding issue.  If I took it to a shop how much should I pay for a diagnostic?

Answer
HI:
if there is amplifier make sure you look at the red light and see if tamplifier is on
also the power of the amplifier comes from the battery see if is plug in or if the fuse is bad the fuse is about 6 inches from the battery if they put one in when the amplifier was install
good luck