Audioquest DC cables - why are there almost no high end DC cables?

Good quality DC cable should have solid-core conductors. Also, you really don’t need 12awg. Actually, you should avoid solid-core conductors that are this thick. Even though it’s DC, it still has a very high frequency draw (for high frequency audio transients). Thicker gauge conductors will not be able to provide high frequency charges as well.

Your choices of Type 4 or CV4 would be perfect for DC cable. They use a combination of 20awg and 17awg in a star quad configuration, that gives you a total 15awg cable. You don’t need more than this for DC on a preamp/source device. The CV4 is discontinued, but it uses better copper (Perfect Surface Copper, which is Audioquest’s version of OCC). The Rocket 33 might give you more total AWG, but it’s not a star quad configuration. In my opinion, you really don’t need more than 15awg for DC.

I generally use 20awg solid-core conductors for both DC and A/C cable. It is the best compromise overall. The 17awg in the CV4 would help low end.

hmm, that's interesting about the conductive negative insulation.

I would assume the NRG-1.5 work also work just fine for DC cable.

yeah, the total cable is 16awg, but it uses 2 x 19awg conductors for each leg.  I was going to mention that the Audioquest power cord is quite stiff.  If you want to completely strip the outer cover and then just use the individually insulated conductors, you're better off just getting straight chassis wire.  Look at the Neotech 20awg Teflon OCC:

http://www.soniccraft.com/index.php/neotech-wire-teflon-solid-cu-c-296_175_183_221

Or, if you want even better wire, try the Unicrystal OCC hookup wire from VH Audio:

https://www.vhaudio.com/wire.html

Then just use as many conductors for + / ground that you need.  Every time you double a wire, you increase the awg by 3.  For example, 2 x 20awg = 17awg.  3 x 20awg would be something like 15.5awg.  You can twist the wires or braid, then cover with heatshrink and/or techflex.  This would be more flexible than the Audioquest NRG cable.

There are 2 x 19awg conductors for the HOT (one blade), and then another 2 x 19awg conductors for NEUTRAL (the second blade).  We call this a 16awg power cord because there is 16awg for each blade.  On this particular cable, there is no ground, so it's just 2 major legs.  If you look at the picture of NRG-1.5:

https://www.audiodestination.co.uk/image/cache/catalog/data/Audioquest/Power/2315lg-800x700.jpg

You will see that there are 4 wires total.  There are two 19awg conductors for each blade.