[Neutered Sputniks]

Correct me if I'm wrong...but if the HU and amplifier have different ground levels applied to their RCA jacks, couldn't that cause a current flow if the shielding were connected to the plugs? Now you have current flow through the shield, and that would almost definitely cause an inducted signal to be pushed through to the center conductor (ground loop). Maybe leaving the shield separate from the RCA plugs eliminates that possibility given the extreme number of manufacturers out there?

If all HUs and amplifiers had their RCA jack shields grounded directly to the auto frame, I could see that the shielding being attached to the plugs would make perfect sense. But, given that such is often not the case, wouldn't it be safer to not attach the shielding?