I recently moved, and installed audio cable in the crawl space and walls. Since I was going to all that trouble, I spent a little more on 14Ga twisted pair wire. Nothing esoteric, the big difference over the super cheap stuff being that it's twisted pair.
My subwoofer still powers up when I transmit, but instead of hearing a lot of my voice when I transmit I only hear a slight thumping. Note the line from the amp to the sub is about 25 feet and line level, not amplified. None of the other speakers (which get amplified signal) have any interference. I'll likely add a few ferrites to the subwoofer input (and inside wiring if needed), but a big improvement over the situation in my apartment where I had to unplug the subwoofer (but antenna is about 20' further away than the apartment too).http://www.crutchfield.com/p_70314250/AudioQuest-FLX-14-2-14-Gauge-2-Conductor-In-Wall-Speaker-Cable-50-feet.html
Note: I did NOT pay attention to the signal direction arrows!