I'm running a Fosgate 600 watt 2-channel amp with 2 old Kicker Comp 12's hooked up parallel off a crappy aiwa HU (cuz my $500 pioneer 8500 got stolen last week)
anyways when i turn my gain up a little over a quarter of the way my subs start thumping like crazy (not with the music but a constant pulsating) and even with the volume all the way down
i have redone my ground because i knew that might have been part of the problem
since rewiring my ground i tested it with my multimeter and i get excellent continuity.
i did notice messing with it some more that there is a slight hum in my subs with the volume all the way down..as well as the gain on the amp.....makes me think
i guess this weekend i will run a 4-gage power lead and see if that helps any