As for subwoofers the trick is to give the driver a perfectly solid enclosure with an infinite mass. Not so easy. Put your hand on your subwoofer enclosure while playing something bass heavy.I have a pair of dual voice coil drivers firing opposed in a sealed cabinet (32mm or 1.26" thick MDF), with substantial bracing. The cabinet is not totally inert, however it is pretty decent. Though certainly no contest for my stand mounts with the steel plate lining it, also with cast iron braces, silicone filled hard drawn copper tubes and birch differential bracing. I have exposed the internals in my system page (the stand mounts, not the sub).
Both lifting the sub an inch, and isolating it at approx >4-5Hz makes for significantly less energy to be injected into the floor, the walls, and everything else.
It is an experiment worthy of the almost puny investment.
You may very well be surprised if you were to experience it for yourself?