The Digital Coax is already shielded......
" A digital coaxial cable offers 75-ohm impedance and a wider frequency bandwidth than the thinner, unshielded RCA cable. If you do connect a standard RCA audio cable, you'll find that you start to lose the signal over long distances, due to the lack of shielding. That lack of signal typically manifests itself in the form of stuttering audio—you're not getting all the digital bits on a consistent basis. You may also notice interference from other electrical devices, including electric lights. The longer the cable run, the worse the signal loss; you may not notice it with short cables (three foot or so).
NOTE
A single digital coaxial cable carries all available audio channels. You only need a...