I've never seen a wire as slow as 30% of C. I don't think your referring to copper wire. Most interconnects are 70% to 80% of C. That's still at least 210 million meters per second. Even at 30% of C that's 100 million meters per second. We are talking LFE audio which is at most 150-200 Hz (Bose). You'll get bigger offsets from the speaker positions themselves than from miles of interconnect delays.
Imaging and soundstage? I'd be more concerned with the cheap amps used for the built in subs.