10 tvs 8 have static when bass hits

hey all ive got a caddy sls2004 with 8 farenheit tvs that whenever the bass hits, white gray and black static show on the screen.  its only at relly loud volumes but its unnacceptable.  ive tried alot of stuff ill try to list

the car has 8 headrest 7 inch screens 1 15' concept monitor 1 pioneer 6 disc indash dvd changer, 2 mtx 8500 12s a pheonix gold 1200 wat amp.  it has a video amp and a 4 in 6 out splitter. dual bateries and new cables with short sanded down grounds to each monitor. 

ive regrounded all video accesories

ive moved the video amp to the pioneers output going into the video swicher

ive unhooked the baterey isolator that separates the 2 batteries in the car

and still i have static.    im kind of at a loss   alli can think to do is add a power filter on each screen.  but i dont want to have to locate 8 of them

any advice would be great! thanks all