I had a problem with speakers popping when using trim tab control, fixed that by installing 63v 100uf caps on 3 leads from rocker switch, popping was really bad ,was awful thru my Rev8 towers,so I am glad this is fixed. But I still have a issue with alternator noise thru boat amp and tower amp, if I disc RCA at amp noise goes away and I have tried RCA isolators but they did not help. Maybe I have one bad amp and issue feeds back onto good amp?? or is this just a ground loop issue somewhere in my wiring. Head Unit is now grounded at same place as amps so maybe issue will be better but I still had noise when using ipod direct to amp, to take HU and WS-420 of the mix to try and identify the problem. Should I try a noise filter on alternator output?? I have 2 new batteries and all power cables are #4 copper and I have a battery switch in case of fire or electrical problems. Any suggestions??? Thanks Dave