It’s amazing cable companies even exist since all cables sound the same… Good Grief. Maybe many cannot hear the difference, too stubborn to want to accept they do or maybe using an old receiver from the 70’s with some Bose 301’s and even Michael Fremer could not either. Hahaha…
I would start with room treatment first if your space allows, then IC’s, Speaker Cables, then Power Cords. Power Cords can make as much of a difference as any other cable location, but if you’re not on dedicated circuits, respectable outlets/receptacles with good contact area then you may not hear the difference at first. You don’t have to spend a lot of money on receptacles as some Hubbell hospital grade outlets are a good place to start.
As always, trust your ears.