This game of how much on which can be fun I guess. It is interesting to wonder why. If the difference is greater under speaker cables than power cords, is that because one carries a signal while the other is 'just power'? Or is it maybe because the speaker cables are twice as long, so more distance for the effects to show?
I leave it to the wonderers to wonder. Me, I will just do it, experience the improvement, and move on to the next improvement. One currently on my list is to replace the BDR Cones under my step down transformer with springs. So many improvements, so little time.