Dave, couple of questions...as I am now listening to a variety of power cords..and trying to figure out which ones are simpatico with my amps.
Do you think the gauge of the cable has anything to do with the sound...thicker is always better, or gauge needs to be just capable enough to support the draw and no more.
Is Silicone a good outer insulator? Seems like a few companies are going that way now. Does the connector plating play a part in the SQ...Gold vs. Silver, vs Rhodium...
Flexibility, how important? To me, this seems like an issue that is rarely considered, but I would think is pretty important.
BTW, I remember my first a’phile speaker cables... the Monster Cables...these were a thick copper cable with a clear insulator. After a while the copper oxidized and the whole cable looked ( and sounded) like s......t
Amps usually like more gauge but it really depends on the amp... a small SET amp still likes a larger gauge cable but tbh PCs don't make as much difference with this type of amp while a big SS amp might respond very differently to different power cables. Most other components don't respond as much to wire gauge but some lower powered components still respond favorably to a larger gauge cable. It's one of those things you just need to try out if possible, but going with a larger/heavier gauge never hurts, except the wallet.
I've found good PC's sound converges to some degree, all of the 3 PCs I carry sound very similar despite different designs, you're paying for fairly subtle differences in the cable... the plugs otoh can make huge differences and the plating can really change the sound of the cable. I've settled on 2 plugs... Furutech NCF which is pricey but head and shoulders better than anything else and Furutech FI-28(R) which has the same "guts" as the NCF plugs without the fancy body and NCF material.
Flexibility is more for convenience and with the Furutech cables you might want some extra length because the cable won't bend and twist easily. My PL cables aren't shielded and are very easy to handle, it is much more convenient, you don't have to plan out the cable path like you do with the Furutechs.
Not sure on silicon vs pvc, neither are really ideal but machine made cables need these jackets. The fact the Furutech cables use heavy outer jackets but still sound really good means the effect might be a bit overstated by some.
I do have demo cables you're welcome to try...