Mike, I have always wanted to try them also. I can now say they really make an easily audible positive difference. I was skeptical about all of this until I put a set of Sort Kones under a phono preamp. I did not expect much and the result was an easily audible improvement. Based on that and other user reports on the Sort Fut I bought them and I am very happy with the results.Cyril, the speakers are completely stable on the Sort Fut after they are leveled. They come with three different threaded adapters, so they can screw in replacing your factory spikes or feet. I think other sizes are available if the supplied adapters do not work. In my case one of the threaded adapters fit my speakers perfectly. If you have large speakers it is better done as a two person job, and would have been much easier for me if I had some help. I also used the locks (not required) and cups (required for a hardwood floor, bot not carpet).Your results may be different, but mine were great.