I like placebo sand mixed with some psychoacoustic pebbles. Then a pure white quartz crystal directly over the amp's transformer.
I also have a shaman come in and perform some cool looking stuff that aligns the polarity of the electrons.
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.