I use an old tig weld table. It was actually used to weld afterburners for fighter jets. Solid steel 1/2" plate. Rigid is an understatement. Because as everyone knows, steel can cause resonance issues, I've "coated" the top & bottom of the steel plate with soundcoat adhesive sheets. I've also done this to the inside of the legs. I modified the weld table by placing two 1/2" thick bars (also soundcoated) from the top plate to the bottom and have my 2 piece preamp rack mounted to that. Everything (except the rack mounted preamp but including the weld table itself) sits on footers with ceramic balls in them. The music is very clear (at most any volume) and the sound-stage is deep, wide, with very well placed instruments in it. I couldn't say that before I did this. The only improvement I've made on par with this that made as big a difference, is replacing the power cords.
System platforms
I recently bought a new rack for my system. It's not an audio rack, I couldn't afford what I would've wanted. I wound up getting what is essentially a workbench. I liked the industrial look and it went well with the tubes and the industrial look of the components. I wasn't expecting the large improvement in the sound. When I did it, it was an aesthetic improvement not an audio improvement, or so I thought. I have the cables, the power cords, a Richard Gray 1200s. Currently I have a decent system, moderate to low end on here but before the divorce I had the crazy system. The ML 33h, Lexicon MC12B, etc. But this was night and day. The audio quality was greater than any cable change I've ever made. If you are on the fence about getting a better rack for your system I hope this gives you a push.