recommendation for turntable vibration damping

hi!
i recently moved into a new home and just completed a project to install insulation under the floor (in the crawlspace). this was done to save on heating costs, but i figured it would also help to dampen vibration from the floor. the floors themselves are fairly cheap with thin carpet over them. (we are likely to install hardwood floors in about a year or so.)

anyway, after the insulation project was complete, i noticed that if i tapped my foot (as in moderate footstep), i could see my turntable shake. i'm wondering what steps i could take to reduce this vibration.

here are some relevant details:
>> VPI Aries on a Bright Star Air Mass 19, sitting atop a...
>> Finite Elemente "Spider" rack built up about 24" with a preamplifier, CD player, and VPI SDS also on it/weighing it down.

the rack is modular (which has served me well during a few moves) and is lightweight.

i'm wondering what my options are for reducing vibration -- i don't think i can afford a big/heavy rack right now.

is something like a bright star 'big rock' advisable? i would imagine loading it down with sand would really weigh down the rack and, presumably, dampen vibration. (they're not cheap, though...especially for the size i need for an original aries. i don't have an outboard flywheel, but i may get one one day.)

i'm open to any thoughts.

thank you in advance.