I'd agree with Asa on all issues........
Try to keep the Speakers and Listening Postion as far away from Rear and Side Wall Reflections
Toe In the Speakers towards the listening position........Tweak, tweak and then tweak some more........even a few mm can make a noticeable difference IMHO
Maybe because I'm on a Three Phase Industrial grade supply, with a dedicated spur going to the Room.........but I've tried many different Power "Regenerators" etc........they didn't make any difference in my applications