So let me get this straight - hooking speaker cables to the antenna input of a tuner is a good indicator of it's audio quality as speaker wire?
I have read where noise was getting into an audio system, and it turned out to be a nearby traffic signal controller. The speaker wires were picking up the noise, which was amplified through the amp's feedback circuit. Their solution for the problem was to use coaxial cable for speaker cable, with the shield connected to common. Please note that it was a combination of a nearby EMF producing device, the speaker wire, and the amplifier's circuitry that caused that audible issue.
If an EMI issue exists, shielding all wiring may be necessary. Some audio equipment is better at rejecting noise than other equipment, so YMMV.