So......what do you use under your speakers?

I agree with Ebm.Symposium Platforms.

I, too, like the symposiums. I have had mine for years and they have made an incredible improvement, both in my sound room and downstairs, as hey have greatly helped reduce the sound in the room under my sound room.

Here is why I recommend them to try, first.
1. a pair is only approximatley $700 or so.
2. You can place them under 2 components if you don't like them, and don't want to bother sending them back.
3. They are very easy to slide around the floor and very easy to move the speakers on top of them. (other soulutions make it very difficult to move speakers around).

The Townsend items look great but it does not look too easy to move speakers around with them.

I, too, had Symposiums and like about twenty or so other isolation devices, sold them or put them in a box in my storage room. There has been much tinkering with isolation devices made of many mixes of vibration absorbing materials. Some even work under some circumstances. Most are better than putting a component on the top of a table or cabinet.

I still remember buying some of Steve McCormack's TipToes that often did help. It has been a slippery slope since then. Unfortunately, everything has a resonant frequency including resonance dampening materials. You get to pick your poison. Dampening helps some until you get close to the resonant frequency. In short, if you like it, use it.

After many years of poking holes in various floors I noticed that there was an "anti-spike" movement afoot (!). Stillpoints make perfect sense, and plenty of speaker makers are now using some sort of "decoupling" on the stands, under the speakers, etc....so I bought 4 butcher blocks that fit the bottom profile of my speakers perfectly, painted 'em flat black, use 2 per side to get my tweeters where they should be (D'Appolito array so no tilt allowed), and bought a set of the proper weight rating Vibrapods, thus allowing the Stillpoints people to keep their inventory stable. Done. The blocks have tiny rubber feet to keep them where they belong (the floor, and on top of each other), and the speaker sits on the 'Pods on the top of the blocks. This renders meaningless whatever your floor is made of (dirt, wood, slate, sand, dried groupie vomit, thatch, granite, concrete blondes, etc.) and my SOTA (according to my friend Art) rig sings like a really well versed bird.

Tbg - I especially liked the one that had no resonant frequency. Was it the Halcyonics? :-). Myself, am having quite stellar results isolating printed circuit boards from transformer vibration, isolating/damping the transformer, and such. Big. Big, big.