Dedicated 20 Amp Line for Audio

Why a "dedicated circuit" when everything gets lumped together upstream of the comnpponent?  Separate line for digital?  Horse schlockey.  If the line goes through a fuse box with "analog" circuits, then the purpose is defeated.  If the dedicated line comes into the house seperately, then it will still be pary of a general cirsuit somewhere upstream without any filtration.   And there's typically enough RF in the air that using a separate circuit will still end up being a long radio antenna.

If an audio user really desires isolation, it might be better to get a hospital grade isolation transformer of sufficient capacity to handle .the equipment load  Or two.  Or three.  Whatever tickles your fancy.  Be careful to check the grounding across equipment in different transformers.

A search on The Cable Company site shows audiophile grade in-wall cable from JPS Labs and Audience. There is also a highly regarded British cable manufacturer who offers an audiophile grade in-wall cable, but the name escapes me at the moment. They are not inexpensive, but in the context of an upper echelon system they are not outrageous.

longplayet - Not sure if I would qualify for upper echelon, but I definitely want to go above domestic grade. Thank you for the leads! I will check it out

A note on 10awg romex.  Yes, the wire is extremely stiff and you may not be able to install it.  You CANNOT fold this wire when pushing the outlet back into the box.  It is just too stiff.  When I did mine, I had to run the Romex straight through the wall from behind into the junction box and then "square bend" one wire at right angles so that there's enough space.  A 12awg romex would definitely be much easier to handle.