If you would to try solid brass machined cones, audio concepts sells them with removable 1/4 X 20 threads. Eight of these cost only $29. I use them under amp preamp and cd with good results.
Preamp Isolation Cones Without Going NUTS
What has been the experience of 'Gonners regarding the best EFFECTIVE vibrational/isolation, cone/footer combination product for use under tube preamps that doesn't cost a fourth the price of the components? Not platforms, but cones, points, tip toes, whatever. Say $100 or so TOPS for a SET.