You might want to try ordering some
"unhappy balls" from Arbor Scientific to compare to the Sorbothane pads. The balls are made of polynorbornene, which is most commonly identified using the Norsorex trade name. Polynorbornene has an even lower coefficient of restitution (better damping) than Sorbothane.
(Be aware that one of the other trade names for polynorbornene is Sorboth
ene, which is different than Sorboth
ane.)
The Arbor Scientific website only offers the "unhappy balls" paired with "happy balls". If you call them, however, you can order them individually. I'm pretty sure the dozen I ordered were $30, which was $2 per individual ball and $6 shipping.
Carefully cut them in half using the sharpest knife you can find, and place the halves under your gear. I usually use 3 halves per component, but vary that based on component weight. I've even tried 4 halves under the footers of my 80 lb BPT power conditioner, and while they deform quite a bit, they appear to handle the load just fine.
If any DFW area locals want to try them, I have a few that I can lend out. I'd be curious to know how they compare to the Sorbothane pads and/or spikes.