Here’s a post from 2004 by Barry, of Bright Star Audio. He started tweaking in 1985.
Since my listening area is on a suspended floor, several of my components are on Bright Star sand boxes - along with aftermarket footers.
In the sand box
I have 2 audio buddies who have built component sandboxes with different types of sand. They claim Beach sand is the most dense and made a huge difference when the turntable and amp were set in them. Has anyone else been down this road? I mean there are several ways to isolate equipment, this is just one of many.