Sorry but I started this thread not to educate about shielding.
You mentioned shielded speaker cables, so it seems reasonable to ask: To what is the shield connected? What would be the advantage of an unconnected shield?
... to give you a clue shielded cables makes for example Synergistic Research ...
Hmmm, I see that its Galileo Discovery cable states:
Shielding: Silver Braid -Quantum Tunneled Ground Plane Technology
It isn't clear just what that is or where the shield would be attached, so I can't answer your question of "what to expect" from its use. Perhaps others here will be able to assist you.