Do good power cords have to be stiff?

Look at Furutech they are pretty flexible and sound great.

@carlsbad

12G or 14G should suffice for most: 15A outlets have 14G single strand copper, whereas 20A outlets have 12G single strand copper providing power to the outlets. That’s your bottleneck: having 10G power cable feeding from a 14G wire shouldn’t do anymore that a 14G power cable.

@dekay 

I added my components to my virtual system, if that's what you mean. . . 

Audio Envy. Both the P series and the M series are very flexible and sound quite good.

Triode Wire Labs.  Pete's cables are flexible, but more importantly sound great.  Open, transparent with tremendous PRAT.

The Puritan sorta reminds me of a wet noodle.

I don't think you could find a PC more supple.