Back in the 80's, Mod Squad produced vibration management / coupling devices called 'TipToes'. They were fashioned from aluminum and did a nice job of helping you mess about with the vibrations moving about your turntable, speakers, etc. I combined mine with some sorbothane 'pucks' to manage a finicky turntable, back in the days of old. Here are some I designed up to print for some speakers I just built. You can easily tweak the cone-height in OpenSCAD to get a particular height. I've include STLs of the original short ones, and a taller cousin.

If you happen to have a metal printer and whip some up, let me know :)