Amp Noise

Hi,

Just a question. I have two amps wired to the same ground and it seems that moving the gain on the subwoofer amp seems to bring some noise to the front tweeters ( there briged on there own seperate amp). Is this something that can happen and will re grounding the Subwoofer amp to its own location help? I know I can lower the gain on the sub amp to remove it, but then the bass is less performing. I did try an isolator, but it didnt do anything, unless its not suitable one I used. Possibly not connected, but can rewiring the ground from the HU to the amps ground location help?

I havent tried giving it its own ground yet as its a bit of a job to relocate it.

Sub amp Jl1000/1
Comp amp Hertz HCP4