Grounding RCAs on the headunit

[RoachForLife]

Read something about having 1 wire ground the 4 RCAs on the headunit on the backside, is this true? Can someone elaborate since Im a little lost

Thanks

[RoachForLife]

this is what Im referring to:

http://i22.photobucket.com/albums/b342/Ultimate157/PioneerFix.jpg