You forgot the tinfoil hat, cuts down on both RFI and EMF...i don’t always listen to my stereo, but when I do, I wear my tinfoil hat. I saved money and made it myself. Don’t knock it unless you’ve tried it! 😉
Oh, almost forgot, my wife had some extra yarn lying around, so I used it to raise my speaker cables off the floor. You see, I tied one end to speaker cables and attached other end to thumb tacks in the ceiling! I actually think it looks nice, except you need to be mindful they are there, or you will inadvertently strangle yourself in a dimly lit room!
Wait, one last one...I place a large pitcher of water on coffee table in front of my listening position. I swear by this, as I do believe it is somehow absorbing the standing waves in that area of My room.