VPI Avenger Reference + Stillpoint Ultra V's

In my experience it's a bad idea. I tried it with an Aries 1 TT and ultra Vs. had bad distortion on any dynamic peaks. The trouble is that you're essentially decoupling the TT from the base, but not the motor. That means that the lateral force from the motor is met by looseness from the stillpoints, interfering with the ability of the stylus to track the groove.  I discussed this with a director at stillpoints (sorry forgot the name) and he concurred with my diagnosis. In the end I went with brass footers directly coupled to turntable plinth and to base. Hope that helps. 

I agree about setting the whole thing on the same shelf, @goheelz .
However I think Stillpoints claims that the effect is greater when you place their footers closer to the component, so they discourage using them under shelves. My own solution to this problem was to buy a used Vibraplane on eBay. It cost less than the price of one Ultra 5, and made a significant and important improvement. Of course you have to make sure you get one in good shape, close enough to transport it yourself (they're delicate). I also found that the brass footers sounded better if they're not sitting directly on the Vibraplane's surface (I use those Weishi graphite blocks).