If your equipment came with a standard 3-conductor cord (grounded), it requires grounding for either of several reasons. Elecrical shock protection, RFI/EMI shielding from the grounded metal housing, or electronic-related reasons. Since, in this senerio, the component is already grounded with the third wire. Adding a shield over all three conductors will further reduce RFI/EMI emission (includes digital and hi-freq switching component noise) into nearby sensitive interconnect cabling and components. Connecting the shield to either end, will have the same shielding effect over the cord's short length.
Some cords will use the "shield" as the third grounding conductor, giving the same results.
On equipment with 2-conductor plugs, any shielding must be terminated at the wall plug, since that's where the "grounding" connection heads back to the breaker box, and earthed.
Important note:
Unless your home's electrical wiring is run through grounded metal conduit behind outlets and walls, no further RFI/EMI protection is provided behind the outlet, as "exposed" Romex offers almost no shielding properties along it's run, and can reside within mere inches (behind walls) of IC's and components.
Hope this helps.
