JPS Labs Power AC IN-Wall Cable

https://www.enjoythemusic.com/magazine/equipment/1002/jpslab.htm

Summary

If your system is toward the lower end of the high end, or you're likely to move within the next few years, and the installation is relatively easy, I'd probably recommend just going with a standard wire dedicated line. For a hundred dollars, and an evening playing with an electric drill, a dedicated line is a true bargain. 

On the other hand, if you've got some nice mid-to-top quality components, and if your life is pretty stable, and if the installation is not too complex, the $1000 to $1500 upgrade to the In-Wall is highly recommended. That's a lot of "ifs", but you could easily spend a lot more upgrading a single component. With the installation of the In-Wall you can improve your entire system, getting the best from every component--now, and when you upgrade them in the future. It is not a "jaw-dropping" improvement, but one that audiophiles with educated ears will easily appreciate. The path to the highest levels of music reproduction is not simple, and rarely inexpensive. The JPS Labs Power AC In-Wall cable definitely took me higher up the mountain and gave me a better view. And for the high rollers out there, building new homes with built-in home theaters and dedicated music rooms, this wire should be considered standard equipment. Don't think twice.

Cardas used to offer a 10 AWG 3 unshielded in wall product @ approx $17. per foot but it is listed as no longer available by their dealer Cableco.
 

JPS Labs also offers an in wall product with 2 10ga power leads + one 12ga ground lead

Beldon has their 83803 12 AWG 3 with a both a foil & a braided shield 

Food for thought

Dedicated 20 amp circuit - Electrician laughed!

I brought my electrician out to my house today to show him where I would like to install a dedicated 20a circuit for my system.  He laughed and said that's the stupidest thing he's heard and laughs when people talk about it.  It said, if you're going to do it, you have to have it separately grounded (shoving a new 8 foot rod into the ground) but even then, he sees no way there can be an audible improvement.

Now, he's not just an electrician though. He rebuilds tube amps on the side and tears apart amps and such all the time so he's quite well versed in audio electronics and how they operate.

He basically said anyone who thinks they hear a difference is fooling themselves.  

Personally, I'm still not sure, I'm no engineer, my room's not perfect, and I can't spend hours on end critical listening...  But, he does kinda pull me farther to the "snake oil" side and the "suggestive hearing" side (aka, you hear an improvement because you want to hear it).

I'm not taking a side here but I thought it was interesting how definitive he was that this not only WILL not make a difference but ALMOST CANNOT make a difference.