I was not aware that a ground isolater was available for a common
speaker wire.What
exactly does it do electronically?Also ,where can you you get one?
My 86 Vanagon,a Country Homes camper,came with a common ground wire for
the rear
speakers.This caused me to blow up one radio before I realized what the
problem was.

If I recall correctly,it was wired in such a way that at tha radio
end,there WERE two
wires for each speaker!The two common wires at the radio end were
multed(joined
together) somewhere where it was not easily noticable.

It finally took a meter to figure out what was going on.

Kent Tunks