Okay, it was a bit of a trick question- I had this email exchange with Roger Russell, of McIntosh Labratories, Inc:
ME: Just read your essay "Speaker Wire, A History." Informative and confirms my
thoughts for years, thanks for writing it.
I provide the sound system ("PA") for a band I play music in. Pro audio
speaker cable is very expensive- also often hard to distinguish from
instrument cord. I have considered using large-gauge zip cord in place of
it- can you address that application? Thanks.
ROGER: There is nothing wrong with zip cord. However, if you are using the wire
where there is a lot of traffic and handling, you might consider low
voltage outdoor lighting wire that has thicker insulation.
I figured that is as good an authority as I need, and I wanted to see if anyone here would, within about 48 hours, contradict him. But the response of running BOTH low-voltage power AND speaker feed thur the same wire is so intriguing, I just had to come clean with this little "test."