Ok, back from Montana and found a pile of springs, cups, and Herbie's products in my mailbox.
I decoupled my speakers yesterday, first by putting the springs and cups under the stands. The rubber furniture leg cups I ordered worked perfectly with the springs as the inside diameter of the cups is just slightly larger than the springs and putting the cups up against the bottoms of the speaker stands created friction that did not allow the tops of the springs to slide against the stands. I got it all set up and the springs seemed to be within their optimal range (around half-way compressed) but the end result was weird after going from a rock-hard coupling using spikes - where nothing was able to move at all to a springy support that almost allowed the speakers sway. While springs are working well under my amps, which are much wider than tall, under the somewhat top-heavy speaker/stand set-up,
the springs allowed a more bouncy support which I perceived as potentially unstable if they were bumped into. Therefore, although the springs I have under my amps are sized appropriately, I didn't really give the spring set-up a chance (at least for now) under my speakers and instead moved on to the Herbie's solution.
I replaced the springs with Herbie's Giant Fat Gliders under the four corners of the stands. After letting them settle in on the carpet overnight, the support is much more stable than with the springs. There is only a very small amount of movement caused by pushing on the speakers (compared to having them spiked), which may be in part caused by having the Giant Fat Gliders sitting on the carpeting. Therefore, I am much more comfortable with the Herbie's Gliders than with springs from the standpoint of stability. I need to give them some playing time before I report back on the sound decoupled vs. spiked.
