I tried Stillpoints under my cdp/dac and under the amp. Made no difference at all to my ears.
I use the Townshend seismic rack corner supports on my rack, this isolates the whole rack effectively. Townshend told me that with the rack fully isolated in this way there would be less gain from isolating individual components. Maybe that’s why the stillpoints didn’t work for me?
Having said that, at the Munich Hi-Fi show I discovered Coral Copulare risers and bought 3 - they are made of synthetic coral. They work well under the cdp/dac and are a bargain (100 Euro for three). They did nothing under the amp.
Having had great success with IsoAcoustic Gaia feet on my speakers I’m interested in their component feet. They use a similar science to Townshend, decoupling with air and pressure rather than with steel, and the Townshend method seems to get better results for me (on a suspended wooden floor).