Those are interesting feet, certain springs for a certain weight speaker. Way back when I was spinning records, I developed a system to reduce vibrations' effects on my turntable. I had a 2" piece of maple under the turntable with 4 springs which were attached to the ceiling. It was a bit tricky just hanging there (don't bump into it...lol) but it really cleaned up the sound by a huge amount. The maple added mass, and the springs added isolation. In those days (late '70s) we were starting to do things like filling our racks with sand and we were using puddy to dampen the vibrations of the top covers of certain equipment.