This is not the only time you've posted about ground loop noise, ed.

It's very promising to note that you still get the problem even with the empeg removed. It means it's a wiring or electrical issue with your car, or your Clarion headunit, and it's got nothing to do with the empeg.

To answer your specific question: Unless there is a wiring fault somewhere in the installation, or the wires on the back of the sled have come loose and are touching each other, then there should be no voltage going to the empeg sled if the empeg is removed.