I haven't tried Stillpoints under speakers but I found them undesirable under source components. I bought a trio of Ultra SS and tried them sequentially under my Brinkmann Oasis, VAC Phi Beta preamp, and Manley Steelhead II. In each case, I found them to create a lot of air and additional separation of instruments, which was good, but at the expense of mid-bass weight and overall tonal balance, which was not so good. Ultimately, I found my system more balanced and natural without them. Actually, that's true of any footers I've tried and I've tried a lot of them.
For context, I have Adona stands with their multi-element shelving, and I use a Minus-K platform under the Brinkmann. Without the Minus-K, I might have liked the Stillpoints more under the Oasis, but I can't say for sure. I know Jay Kaufmann at Audio Revelation loves them under his.
