I have 4 sponge hockey pucks under a 15" 400 watt sub. It is on a wooden floor on a second story. The differences in sound between the pucks and the original solution i used of blue tacking the sub cabinet directly to the floor (its a front firing dual ported enclosure that weighs around 80 pounds)was inaudible. In fact it sounds just as bad either way. I suspect that cones will mimic the blue tack effect.

I loved the sub when i first got it, but now 1 year later, it is usually set very very low levels. It just got musicically boring, kind of like tympani...

Just a question; did you set up the main power amp with the correct capacitors to roll it off per vandersteen's instructions? I have heard of people who 'blow this off"...big mistake.
I have 2 2W's with Vandersteen model 3A's, and I found that they only work right when placed tight in the corner; about 1 inch from the walls (but we are talking concrete slab floor).
You might try using a 1/2 inch thick sheet of ensolite closed cell foam under the sub with no spikes; I know of similar cases where that has worked (the stuff is sold by REI for backpacking sleeping pads).

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I have a sprung wooden floor. I removed the spikes from my Vandersteen 2W subwoofer and set it atop three "sandwiches" (of two each) neoprene/cork isolators. This improved bass clarity and also the imaging of my main speakers (Maggie 3.5s). Does anyone have any experience with using Aurios or other isolators on a subwoofer?

The ASC SubTrap is outstanding and the Aurelex SubDude is almost a no-brainer. Made for the purpose.

Kal