Shielded speaker wire?? . 70 volt doesn't require a shielded pair. Some regions might require bonding or even continuous conduit. But shielding doesn't apply to a 70 volt audio system. You might have confused this information with "bonding" , but I doubt that also.

However, If you are running other signals including other pairs of 70 volt conductors in very close proximity to a 70 volt audio signal,, you should be aware of the fact that a 70 volt signal can induce energy into an adjacent pair of wires. So,,, never run discrete zones of 70 volt audion in the same bundle for a significant distance. 50 feet or more. An RF video pair should be OK,, and a CCTV copper braid coax won't have a problem , nor will a properly balanced line or mioc. level signal, but always attempt to provide at least a foot of seapration on any of these parralel runs in excess of 50 feet.