I have enjoyed my amp and head unit for a few years now but all of a sudden there is a horrendous buzz or hum when you turn it on. It is ok when the volume is turned to zero but as soon as you turn it up to even 1 it makes this awful noise.
I have isolated the problem to the rca input jacks going between the headset and the amp. When I unplug and plug in these jacks at the amp, there is a loud buzzing noise and it makes the subwoofer move. I have checked the jack wiring and all seems ok, no breaks etc.
You're sure that the RCA cable is still good? It's also possible the RCA input on the amp could be a bit loose. Best way to find out is to run a known-working RCA cable to test (though I understand this may be hard since you might not have RCA cable that long hanging around anywhere).
Another possible problem is a bad ground either at the head unit or amplifier.
It's not a Pioneer head unit, is it? It's possible you blew a micro fuse on the unit.