Ground loops occur when two components are grounded in locations with different ground potentials.
The right way to fix a car audio ground loop problem is to ground everything in the same place.
In-home audio systems, ground loops usually happen when two components are plugged into different outlets.
Fixing the problem may be a simple matter of changing where you have things plugged in.
Unfortunately, the matter of grounding is a little more complicated in-car audio systems.
This is a situation where an ounce of prevention is worth a pound of cure.
Ground loop isolators consist of an input, an output, and a transformer.