My house has a bunch of existing "in wall" speaker cable runs. To redo it would be a real pain, given the finished basement. And the cables go pretty much where I want them to.
However, I have a couple concerns. The cable used is pretty basic 16 gauge that looks like it could have come from anywhere.
1. Do generic speaker wires degrade in any way? Will this cause problems over the long run?
2. I read in another thread that there are wires that are better for in-wall use. I imagine this refers to noise from AC wires. However, is there a heat or fire risk with these "cheaper" wires I have in place now?
Standard zip cord and similar products will degrade in time. Depending on where you live the temperature in the wall and attic space can do serious damage to the insulation causing it to crack and lead to short circuits. Living in Pheonix makes the problem worse than living in Fargo. I would certain use a continuity tester before I hooked anything up to these cables.
The code for new construction in most of the US now requires a CL rating on the cable to provide some fire retardant properties. If the cables were run properly in the first place, they shouldn't pick up stray RF interference. Any heat generated within the cable would come from you running too much voltage through too small a cable. If you have 16AWG cables, you should be OK.