TVfreak, the problem with the dots (as well as Sorbothane, etc.) is their rather high resonant frequency (see the technical info on Townshend Audio's site, where graphs of the resonant frequencies of Sorbothane, spikes, and Townshend's Seismic Pods are shown). It is not down where it should be, in the low single digit frequencies, but rather high enough that it causes resonance in the audible frequencies, leading to the well-known bass bloat heard with rubbery isolators. Spikes don't isolate at all at very low frequencies, being very efficient couplers below a certain frequency. The theory of a spike being a mechanical diode (allowing vibrations from the speaker enclosure to travel down the spike, but not vibrations to travel up it) has been proven to be untrue.
If you want to try roller bearing isolation, you can make a set on the cheap (see Barry Diament Audio for details), or pick up a set of three from Ingress Audio Engineering for $75 plus shipping. If you do make your own, and want the lowest resonant frequency possible, make the surface the ball bearing rolls across flat, rather than bowl shaped. The surface the bearing sits on will need to be perfectly level to prevent the speaker from being able to roll off the bearing---you may want to add a ridge around the flat plate! That's fine in theory, but not a very good idea in practice. If the bowl has shallow enough "walls" (Barry suggests the bowl be formed to the profile of a 2" diameter sphere), it's resonant frequency will be in the very low single digit range, providing excellent horizontal/lateral isolation (but coupling in the vertical plane) for any loudspeaker, or even subwoofer. With a slight bowl-shape, the ball bearing the speaker enclosure sits on will still be able to move horizontally/laterally (contrary to what you may have read in a previous mistaken posting), it will just have to "work" at climbing the incline of the bowl's wall, which it is obviously free to do. That merely raises the resonant frequency of the roller bearing slightly, which will none-the-less still be very low, much lower than the dots. A set of three DIY roller bearings good enough to test their theory for yourself will cost you only five bucks or so.
