I have one on my LeMans stand under my Nottingham turntable. What it does is liven up the sound a little. I've never compared to anything other than the stock acrylic shelves. I suppose they do sound a little better than acrylic but they sure are expensive.
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?