I"m getting a lot of rumbling in my subs when you switch tracks or when the rpm's increase. It started when I switched amps, I used to have a competion ag series amp hooked up the same way. But I switched to a kenwood 846 4 channel and have the 1st channels bridged and one sub off them, and the other two channels bridged and one sub off them. I'm thinking my rcas in the amp might be loose, I have the ground right beside the seat belt bolt and cleaned good. whats going on?