In wall cable

The link to the soundstring cable looks like 3 conductor, which seems like a waste. There 2 conductor bulk cable is

http://www.soundstringcable.com/gen2/Bulk-Gamma-2-12-standard-speaker-cables.htm

Belden 12 gauge CL3 in-wall is a standard, non-exotic cable. Parts Express and Blue Jeans have it and you should be able to find it locally at an electric supply house. 10 gauge also available.

Analysis Plus

Elescher,...that looks interesting though the link above did not work until I tweaked it a bit;

http://www.soundstringcable.com/gen2/Bulk-Delta-3-12-High-Out-put-30-Amp-Power-Supply-Cord-Power-Cord-Cable.htm

It looks in-wall rated at seems to be 10-gauge. Let us know how it works for you as it could be a nice, more cost effective alternative to Romex.

I am just getting ready to install two additional dedicated lines in my sound room. I bought 200 feet of this. http://www.soundstringcable.com/gen2/Bulk-Delta-3-12-High-Out-put-30-Amp-Power-Supply-Cord-Power-Cord-Cable.htm.

Power, speaker or interconnect?

AQ makes several options that look very good.