I have a BDR "The Shelf" under a Project 9.1 with Benz SM the sound is lively with quiet backgrounds and good dynamics. I use Simms Novcom Pucks under the Shelf for isolation, you could use Sorbagel or BDR Cones but I think Sorbagel(used on GP Audio racks) would provide better isolation and not make the music lifeless in combination with "The Shelf". The price is a little more than half "The Shelf for Source" price.
Grand Prix Formula vs BDR shelf for source
under a turntable specifically...how do they differ sonically? I want a good shelf atop my rack for my TNT to call home. both are available in sizes large enough, and both are obscenely expensive, although the gp is $600 less retail. any others I should consider besides symposium?