Lew -- Not sure what you mean in your last post. There are presumably two rca plugs (for left and right), plus a turntable ground wire, at the phono amp end of the cable from each turntable. The "ground" (non-"hot") side of the cartridge output for each channel is connected to the outer part of the rca plug which corresponds to that channel through the cable shield.
Regards,
-- Al
Regards,
-- Al