Which of these power cords ?

 I have an audio only subpanel with 8 dedicated circuits of 20 amps each per outlet in the listening room isolated from the lighting and HVAC servicing the room which goes to another subpanel.  The audio power outlets have Synergistic Research Blue duplexes.  The wiring is 10 gauge.  I built the room for listening purposes only.  The 42,000 LPs/78s/CDs are housed in an adjacent storage room and record storage Tuffshed.

I have the DH Labs Red Wave power cable on my amp. It's the biggest single improvement I've ever experienced, I was amazed.

Yes, at least 2-4 dedicated home runs of 15/20 amp 10/8 gauge wiring and hospital/audiophile grade outlets to the audio system is a big improvement—I’ve done this twice in the last two homes I’ve lived in (one was a rental with my landlord’s permission) and the results are amazing—easy to listen to/hear over the standard outlets. Both electricians thought I was “nuts” and I got them to listen to the “outlets” after the install and the amount and impact of the bass response on my 200 watts Class A amplifier was easily discernible to their “non-audio file“ ears, and they admitted they would not believe it unless they heard it and installed the wiring themselves.
I would upgrade the wiring to your audio room first, before trying new power cables, if possible, and then buy “used” cables and listen for differences in your set up. The improvement will go well beyond bass response...that is merely something that non-audiophiles and audiophiles alike can easily hear. 

The power that is spec'd and rated for your home is done at the outlet, not the transformer down the street, or the all the way back to the dam spinning the giant turbines, or the coal plant belching crap into the sky.

All of this nonsense about all the miles, nodes, transformers and such are just another B.S. line of thought (if you can call it thought) that naysayer latch onto as a form or "gotcha" ridicule that works on those easily swayed by such tactics.

As others have said, it's the first few feet your amp (or source) sees which relies on that outlet meeting said specs and ratings as the amp was designed to work with them, and not a different set of specs anywhere back on the line.

All the best,
Nonoise

Nobody gives you more for your money than DH Labs.  Call the guys at The Cable Company and ask them what they use at home.  I would imagine they can pick from anything, but the guys I have spoken to use the DH Labs Red Wave, so that's what I bought.  Couldn't be happier.