Here in the old Europe we have a bunch of companies, especially from the UK and the Netherlands, that are in the growing process of proliferating myths about the technical contents of power cords, audio interconnects, and - obviously, speaker cables.
I have been caught in the net, in several occasions.
I would like to report some of my experiences and understandings.
#1. The power cords to the gears add only 2 meters or 6 feet, or so, so this is a small fraction of the entire path to the outlet
#2. Shielding a power cable is not a good idea, as it will add much more capacitance to the cable vs. minimal positive benefits
#3. Ferrites to stop RF being picked-up by power cords and other audio cables : these will significantly round-off the high-frequency content
#4. In my installation, I have run a dedicated power line, two in parallel actually, each one made from 2-conductors, 12 gauges twisted solid copper, to the A/V system outlets. (My gears are all class 2 double isolation chassis with no provision for the earth wire.)
#5. These dedicated lines end up on outlets with above-standard high copper content as well as with silver plated contacts
#6. I now build all my power cords from 12 gauges solid copper, 2-conductors, twisted. (You need to accept the fact that you need to bent it to route it to the gear.)
However, and ultimately, the biggest role is played by the gear built in power supplies : do they have enough low inductance energy storage and enough fast response times to provide current to the electronics ? If the answer is yes, very minor advantages will be noticed, if any, by replacing the standard $2 / tons FOB Shenzhen black cords that are supplied with the gears with esoteric or DIY power cords.