"Crossing wires at 90*: another thing that can easily be done (instead) is to keep them all at least an inch (2.5mm) 3mm apart. Easy to do with a plumbing-pipe foam insulation tube, cut up into short bits.. then place the tube bits around the wires where they touch or cross. I even use a bit of packing tape if the tubes want to slip off each other (just on the tube things). Also on the ground: using a paper towel roll tube, taped up with packing tape, then cut into 1/2 inch (1mm) high circles, under the cables on the floor. You could even wrap them in black paper to look cooler. Remember we owe this idea (raising cables off the floor)to Enid Lumley.
These 'nearly free tweaks are great.
To comment on 'expensive tweaks': well a fool and his (her) money are soon parted. Try the free (or nearly free) tweaks first!!
Also footers. Search the web and find Chemical rubber bottle stoppers sizes 8 to 10. They cost about a dollar each. Or, find the industrial urethane vibration control half-domes and pay only $2 to $5 each.
I use a LOT of size 10 bottle stoppers. Love them.
Cheap IS better. I then can spend the money an better equipment.. instead of trying to $$$ money-tweak my way to better sound.
For Hypothetical Example: A setup with $1,000. each pair cables, $2,000 speaker cables and a $3,000 amp? or a set of $200. cables, $400. speaker wires and a $$5,000 amp?
I refuse to spend money in the wrong place!!
I do confess I also do not bother with room treatments, however old and foolish this makes me look.
I would make some of the wall panels with the different height blocks.. but I am too cheap to pay the retail, and too lazy to make them. They look cool to me.