In reply to:
Good point wid. Possibley, worth a try to gently wiggle and see if it could be confirmed to be the problem. If not, the issue still could be some component inside that the sub is vibrating but is not in direct contact with the YPbPr cable.
The problem may not lie in the connection but rather in a component within that particular circuit on the board. For example, if it were a poor solder joint on a wire-wound resistor in the power supply for that particular circuit, then that would cause the problem for that input alone.
If there is some RFI from the sub's anti-distortion circuit (if applicable) then proximity of the sub to the TV could be the problem.
