confused about equipment racks

I have been considering either a commercial or a DIY rack for my components.
The problem is do you isolate or couple?
I'm good with speaker spikes which couple the speaker to the house.
But what about a CD player? Isolate? Couple to something massive? Why do I read about Maple butcher block?
I've read about people who swear tennis balls are good. Others use hockey pucks or handball balls, whole or cut in half.
Steel shot, lead shot, cat litter and a host of 'custom' ($$$$) products to fill tubing.
All sorts of weird (to me) theories about resonance / damping / microphonics and related phenom.

Any opinions or stuff I can READ to try to straighten this out. Please, not too much advertiser hyperbole.

thanks in advance::