Speaker Wire

There is a really good article on this subject I will simply link to but also give you a quick rundown of its conclusion.

 

Here is the link http://www.budgetphile.com/2013/11/budget-wiring-reality-of-copper-clad.html

 

Basically CCA (not pure copper) wire is perfectly fine and the only issue is greater resistance (higher ohm levels) after 100 ft lengths. In the end it is still cheaper to use a higher Gauge CCA wire once running longer lengths over 50 ft or so such as a 12 AWG instead of the standard 16 AWG.