Speaking of cone tips and hardness, I got a set of the original Mod Squad Tiptoes when they were introduced in the 1980's, and installed them under my 140 lbs. apiece loudspeakers, with steel discs under them to protect my hardwood floors. It didn't take long for the tips of the soft (aluminum) Tiptoes to become flattened. Oh well, nice try.
The DH cones work especially well under my Townshend Rock Elite turntable (even better than those by BDR), whose unsuspended plinth is an upside-down steel frame (like a rectangular cake pan) filled with plaster-of-Paris and bitumen pads---very non-resonant. The p-o-P and ceramic cones make a great coupling