Hello,
For your speaker wire, I always install 14/2 guage UL rated in-wall speaker wire.
Here's why. Speaker cable, or wire, is measured in gauge. The smaller the number the heavier the cable. 14 guage (14 AWG) wire, because it is easy to manage, terminate, and has low impedance, is considered to be the standard. However, make sure that the speaker wire is UL Class 2 or 3 (Cl-2 or Cl-3) rated for in-wall use. Cl-3 rated cable has an extra insulating (usually grey) sheath around the two insulated (red and black) wires, and the designation "Cl-3" will be printed on the cable.
Side Note: cable marketing, fact vs fiction.
There is very little science in the "art and science of audio cables/wires. Unnumberable "double blind" test have proven that while the average consumer can detect a difference between adequate and inadequate wires, they cannot discern the differences between generic and designer-brand versions of the same basic wire types. Just make sure that the following specifications for speaker wire are met with the wire you choose:
1. loop resistance (less than .2 Ohms)
2. inductance (less than .25 microHenries per foot)
3. capacitance (less than 50 picoFarads per foot)
Aside from the tech mumbo-jumbo, be rest assured that most installer-grade CL-3 rated 14 guage stranded speaker wire meets all of these requirements. And as long as the wire meets the above standards, the most the sound will be distorted would be no more than .5dB which is 1/6th of what the human ear is capable of detecting. Even if the wires did not meet these specs and were significantly worse, you may have a drop of 1 - 2 dB which is still well below the normal 3dB that is detectable by the human ear.
That said, don't rush out and buy the most expensive speaker wire because it has been tested and retested to meet strict lab tests. You will never notice the difference between the name brand or equal generic brand.
Hope this helps.
Take Care,
Shawn Mosqueda
WireSmart LLC
If you have any other questions feel free to contact me by clicking on the profile link below.