I think all the proponents of expensive power cords should remove the wall plug plates from any two live 20A house sockets, and stick their fingers in one, then the other.
Blind, double-blind or otherwise makes no difference to me.
Repeat the experiment about 50 times.
Report back to us with the measurements for when they felt a difference in current draw.
If there's a statistical significance found in their results, then I would have to agree that a power cable has the potential to alter the current passed from the wall socket, since they've felt a difference in current draw between the two sockets a sufficient number of times (to my satisfaction anyways).
To that end, it could make a difference to the sound emanating from your system due to different power cords having different RLC characteristics. Whether or not it's for the better....
Well, let's just wait for the results of the first test, shall we?