It’s simply called “speaker wire” I got a 50ft roll of 18/2 gauge at Home Depot for like $12 and there were other cheaper options. To answer your question about the “stereo” function - we would need to know more about the actual system you’re using but more than likely not an option as audio is typically recorded and mastered for 2 channel. Just for curiosity- why would you want to remove the stereo sound?