( 2 subs). At the back of the head unit is some kind of sony box which I assume is a connvertor for RCA input to low level (it has RCA leads entering it and loads of wires exiting into the loom). Well everything was hunky dory except the other day I notcied the bass was extremely poor from one sub box. I took the head unit out and checked the connections, all seemd ok, then all of a sudden the second sub box stopped sounding right. I can see that the subs are moving but they make a terrible farting noise. I assume that if the amps were at fault then I wouldnt hear any sound, could any one help me or point me in the right direction? I have tried to search the forum but no joy.