Heavy duty amp stand, Sonic benefits?

I hav3 a heavy walnut and maple stand and for sure much better isolation then glass , that being said iso acoustics makes different models of isolation to put under your equipment, still points too  works , even Herbies tube dampers on tubes work, and Herbies  also sell footers under $80  good for dacs, preamps.

I have a 24x48 and 3” thick solid maple audio platform. It has 5” coasters. I didn’t notice any improvements when I first got it but it sure looks nice

Stands make huge difference

Steer clear of metal and perspexy glassy shelves - horrible

I have had 2 purpose entirely bamboo racks built for me and I am happy

Mostly I have found that stands save the amp from collisions with the vacuum cleaner.  And can look good.

Yes, and well isolated from your main rack. I use a mapleshade custom 4in thick maple wood amp stand with spiked footers for my 114lb McIntosh MC 500 and it serves it well.