Best Power Cord For Digital Amps

You are so correct in your assumption shielded power cords are a must. Oddly just the opposite is true for interconnects, but that is another topic.

I have found that different PCs can make a difference, but it is always a, "More of," what is there. After all, we are talking about the transfer of raw power.

I have Shunyata PCs feeding my mono amps. I made the power cords for my preamp, the H2O Fire, and all other components. I used Belden double shielded cords, and Watco plugs from Parts Express. The shielded cords are necessary for all your gear.

Another fellow audio enthusiast brought over some $800 used PCS, and we all noticed a boost. I will find out which that was and get back to you.

Fusion Audio sound very good on my H2O's

Elrod Power System - not question about it!!!!

I run Gilmore Raptor monos, and the instructions clearly state not to use any aftermarket PC with them. They supply a heavy-gauge, fully-shielded cord with them.
I compared them to DIY Belden 83803 PCs and found that the stock cords sounded similar, but had a bit more bass. YMMV