Welcome to the tweakend!

I tried the inner tube thing back in the 90s. I found it just about impossible to balance components where the center of mass was significantly off center.

 Very easy, you need to "think out of the square", you buy an inner tube that is smaller, 2/3rd’s the size of the plinth it’s under and locate it more to be under the heavier section of the load. Inner tube is far better at isolating than thick rubber balls.

Cheers George

Vinylzone, what are you planning to put on them?

The trick is getting 6", 8" and 12" inner tubes and choosing the one that best fits the size and weight distribution of the component. Fill with 3-5 PSI and balance the component on the tube. I even went so far as to fill a 6" inner tube with 90 weight oil and that was trans-formative. However, I was concerned that over time the oil would degrade/soften the rubber and I would have a huge mess on my hands at some point. 

Now that I think about it, I wonder if water in the inner tube would be a suitable replacement??

mijostyn,

BAT VK-30SE preamp on one, Herron VTPH-2A on the other. I may also try it under a secondary turntable I use for checking out used records at some point, but right now I don’t have a pile to check out.

georgehifi,

I may try that again at some point, if only to compare to the balls.

@dekay 
My system is in Flux right now.  Are you talking about virtual systems? If not, where?