I live in an area with clean power, so have not needed a power conditioner.
I also easily hear the difference between cables.
But I have to say that if there was one application that I might think different power cables (of sufficient capacity) would not matter it would be on a power conditioner. I wonder what impact that a power cable would bring going into the power conditioner that would not be filtered out, neutralized if you will, by the filter/conditioner itself?