Vibration Isolation

These are what my local stereo sold me. At  $4/each. 
I use them along with a second tool. Walmart replacement
tire tubes. Size 12.5". Cost $4.50 ea.  That I have under the 
Oppo CD player. The retailer I mentioned that is here locally
uses it under his turntable. That failed for me however.

Why not try these stacked, where the lines are parallel, then at right angles.
Hear a difference?

For me, the best use is on top of electronics, IECs.
I use them inside my power amp, on the rail cross member near
the transformer.  Tame the micro vibrations, hear the difference.

Try these for yourself... what component(s) would you have to upgrade,
in order to achieve the same results, and at what cost?
My answer: these squares operate on a different level.
I am thinking the positive effects may be more apparent
on high quality components, for example, on the glass top
of my Powercell UEF 12 power conditioner!

I use these under my Edensound terrastone platforms ... they work and sound great, and are much better than the rubber/cork-filled squares.

About a year ago I purchased the blue and the natural cork color (different materials) from the same company that is in the opening post. They do work well, the company also offers a variety of sizes, for example, I have one that's 18" x 18" etc.
One word of caution seems like all of these types of isolation devices (rubber/cork/rubber) will leave black marks on your wooden platforms, that I have nor figured out how to remove.

It can be demonstrated fairly easily the best approach, generally speaking, to vibration isolation and resonance control is the deliberate and coordinated implementation of a combination of mass on spring type isolation and vibration damping for the top plate of the iso system. The art of isolation comes in when interfacing the component to the top plate and interfacing the iso system to the floor or rack, not to mention the choice of damping method and material for the top plate. This attack will address very low seismic vibration, acoustic vibration and “residual vibration” on the top plate that arises from several sources. If it was easy everyone could do it.