Chuckaolcom; here is wht I did and i is the best $225 I have ever spent. I had Andy Misco at http://www.hhgstands.com/ build me one of his stands with an insert space of 18"x18". I had intended to use it as an amp stand but I gave to large a measurements and it did not fir under my desk. Anyway I went to a local cycle dealer got an 16" tube put around 5psi in it put the granit on top and then my TT. One you get all the vibration control you need (get large spikes). At $200 for the woodwork $20 for shipping and $4.95 for the innertube not only does it work great the craftmanship is unsurpassable. When I have another made I will have the well at least an 1" deeper so I can use 1.5" granite instead or .5". I am also going to tweak my stand by getting 2-3 more innertubes and gable tying them so they are oplong and not circular so I can put 3-4 tubes in the well. Also one thing you might look into (I'm going to order some as well) are the seashocks. Look up www.seashocks.com. Very interesting.
Hope I helped some
Good Luck
Hope I helped some
Good Luck