I've tried many isolation schemes over the decades, I prefer sand boxes to granite, concrete, various woods, soft and hard plastic products. The platform which sits on top of the sand is critical, I have platforms made of various thickness aluminum plates, all with vibration sinks attached via structural glue, also have various wood platforms, various thickness maple and baltic birch. Finally the footers, have many to choose from, generally prefer Stillpoints. Finally I have choice of avoiding sand boxes, platforms or footers altogether, components hung from custom built stands via high test monofilament fish line. All isolation solutions editorialize to some extent, the fish line method editorializes the least. The entire system sits on a large concrete slab over a suspended floor which is reinforced with a number of floor jacks placed in strategic positions.
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.