Originally Posted by CdnoilRAM
take a short length of bare electrical lead (not single strand wire) and wrap it around the outside of each RCA post and collect them at any exterior casing screw, this grounds the negative side of the RCAs to the case if you have an internal RCA ground fuse gone. Then take the a lead and from another exterior case screw and run it to a clean body ground, this will ground the case to the frame, and should alleviate any RCA signal distortion.
Multiple RCAs won't cause any issues, they are just signal outs, but if you do get a new head unit, that would be a simple way to tell if you have RF interference or RCA noise.
I meant that as in either way i might be getting a new head unit so i can amp all 4 of my 6x9s. AND still have a sub out as well, instead of a front and rear/sub. My bad.
Would you recommend to ground the RCAs only if I've blown that fuse? Where is that fuse?