duece9s

so i've tried: uplugging rca; no change hooking phone up to amp with rca to 3.5mm; no change moving both amp grounds to same spot; no change rerouting 4 ga +/- to go thru the trunk mat all in the same spot infront of amp stack; no change. Rca's no longer cross over grounds probed grounds between points A+B and it was 3.5mv. is it something with my car being a unibody and the alt just being grounded thru the case? do i need to add a hole to the trunk shell to ground both amps? removing second battery and second amp did nothing

i rerouted the rca along the left side of the car from the radio so it doesnt cross the positive from the battery, got rid of ground splice, sanded paint off bracket where ground attaches. still sounds like crap at 0-25% volume. do i need to move the ground shown in the first picture to somewhere else?

i found a loose ground as i had most of the wires out recently to put ferrules on the wires going to amp. Is adhesive lined shielding foil tape worth anything? one of them is a MT-1000 (700@2ohm), the other is ZD-750.4D (400@4ohm). i got a second because my car has electric power steering and i wanted more reserve capacity. It starts like a champ in -20 despite both those batteries being at least 10 years old. edit; i'm going to remove that ground splice, going to sand the paint off of the bracket where the ground attaches to, and possibly redo the amp mounting to stack them vertically instead of beside eachother.

my factory battery location is in the trunk, and i added a second battery, and i have had bad alternator whine for forever. + from alternator is on the right side of wheel well,and then follows rear seat. There is a bundle of wires that i run parallel to alt +. i tried to sketch them as normally routed, with the amps in roughly the right location. transition from dashed to solid is where they are above the trunk floor liner for +/-. i was thinking about changing the RCA running on the drivers side from the front of the car, instead of passenger side. pink:rca green: speaker wires blue box: sub grey: grounds reds: + long story short, am i experiencing this because of rca in proximity to alt +, or the mess of wires coming in/out of the amps?