I have always used Sorbethane products and recently switched to some Ginko footers and so far I can't say I am hearing difference good or bad. I will switch back and see if that is more telling. By the way it is a Running Springs Jaco.
Yes under an Audience AR6. I have used Stillpoints a lot and have a bunch. Biggest difference was speakers, then AC conditioner, then amps. Little change under MSB analog dac or power supply. Some benefit under MSB UMT+.
I purchased stillpoints mini ultras and put 3 under my synergistic powercell3 and the difference was obvious. It is not night and day but definitely a moderate improvement especially in bass information and clarity. I heard no brightness issue.