Perlite Speaker Stand Filler

Perlite is too lightweight to have much effect. You're better off using something like clay granules (kitty litter) if you want to steer clear of sand or lead shot.

I like pea gravel. It is not as messy to work with as sand, is cheap, and has good damping properties.

I used cheap non scented clay kitty litter to great effect.

I should have noted I'm NOT trying to add mass,stands are heavy enough,simply trying to damp resonance of the metal tube.

I've thought about this. To damp ringing in a metal structure, you need mass applied to the structure. Lightweight materials simply won't have much effect on this. Gravel, because of the space between granules, is lighter than sand but does very effectively damp the ringing. Hence my solution.