I've been using/experimenting with a vibraplane-like product under my Galibier. It's made by a company called Herzan and is an automatic model like the 2212(?) from Kinetic Systems. There are also other producers out there like Benchmate, Melles Griot, Newport, Micro-G, Oriel, Servabench and TMC. They will come up on Ebay every once in a while and can usually be had relatively inexpensively. I think I got mine for $99, shipping was about the same IIRC. I feed it with a Nitrogen tank because it's quiet and cheap(about $10 every few months).
The instructions for my particular model said it wanted a 200lb load so I had a piece of aluminum cut to the same size as the platform that made up the difference(TT=~105lbs, Alum. plate=~85lbs). It is self-leveling, however, if the load is unbalanced by too much it won't be able to compensate and thus requires a bit of experimentation to find an arrangement that works.
In the end, the biggest difference I notice is that the lower frequencies are less boomy. Without it bass info tends to feel "slower", meaning that a bass note will hang around a little longer than it should and actually seems a bit louder, but fuzzier. If I didn't have the Herzan I'm not sure it would have ever bothered me really, which may be a testament to the design of the TT, however, I do think it makes a positive difference, just fairly subtle. Of course, subtle to me may be huge to someone else. I'd be surprised if you couldn't hear the difference in my system, but YMMV. BTW, I have suspended wood floors - more solid than most, but it isn't a slab:-).
Matt
