You want a lot of mass under the speaker.
I used a concret patio slab, 2" thick and 24" around. about 90 pounds each up on tiptoes over the carpet. then the speaker base stuck on that when I had Infinity RSIIA speakers.
The extra mass of the concrete really keeps any cabinet vibrations out of the floor. and helps dampen the floor in front of the speakers too. so the woofer first reflection makes less of a problem into the floor too.
I painted my slabs black.
Another means is use Magnepans. they have good sound but tend to not shove bass into the walls or through the floor.
I used a concret patio slab, 2" thick and 24" around. about 90 pounds each up on tiptoes over the carpet. then the speaker base stuck on that when I had Infinity RSIIA speakers.
The extra mass of the concrete really keeps any cabinet vibrations out of the floor. and helps dampen the floor in front of the speakers too. so the woofer first reflection makes less of a problem into the floor too.
I painted my slabs black.
Another means is use Magnepans. they have good sound but tend to not shove bass into the walls or through the floor.