Footers under my speakers double the perceived value of my speakers!

I'm using good old American steel under my stand mounts. Less than 1/4" they have elevated the speakers in position, and a lot in performance.
Smalley wave springs on Ebay cost me under $20 shipped.

Isolation works very well for me.

All my electronics are isolated on springs, as is my sub.

No its not height it is floor interactions.  

I've used same speakers upstairs on suspended plywood and downstairs on solid foundation  (thin but dense carpet and pad).  Same height.   The same isolation under the speakers does nothing on the solid concrete foundation.

What works for me with a heavy load (70 pounds of concrete) is the coupling-decoupling processus in the different densities materials i was using in sandwiches under my gear:

4 quartz feet -granite plate- sorbothane-granite plate-cork plate-bamboo plate- sorbothane- speakers or amplifier or dac...

They are on my desk with all the other component.... No vibration under my fingers....Not perfect but very efficient at low cost....

Hi-Fi for the poor is my motto...  Homemade creation is my act.... :)

The IsoAcoustics website has an interesting interview with their CEO (Dave Morrison) being interviewed by someone from Music Direct; so, you get viewpoints from both a retailer and the manufacturer. Dave uses the adjective "smeared" a lot in the interview, which I find both accurate and interesting since that is a rarely used word in the audiophile vocabulary. 

The fact that Dave started in "pro audio" might win over some skeptics, or how closely he has worked with Paul Barton of PSB speakers. What ultimately convinced me to buy the product is after Stereophile named it a "product of the year" in 2018, I never once saw this product show up on a used audio website, nor did I see any retailer ever put them on sale. Both seemed to be indicators of a good product and I'm glad I trusted my instincts....but, I wish I had of done so sooner.