The shelves have to go. Your root cause problem then goes away.
MDF is largely reflective. That's why Andrew nearly poked his eyeballs out and lit his hair on fire dealing with standing waves in the M100. This answer is purely academic because, like I said, get rid of your shelves.
Regarding your turntable, get rid of it and your problem is solved.
Regarding cable routing, keep high current carrying conductors separate from small signal conductors and all will be fine. If they have to cross, cross them at 90 degrees relative to each other.
P.S. I have Axiom stands for my M5s and I like them. I'd like to see Axiom cost-reduce their stands without impacting their effectiveness.
