I just put a set of 3 small BDR Cones under my Parasound 2100 preamp. The BDRCs replaced a set of 4 Mapleshade IsoBlocks (those sandwich blocks w/ cork in the middle and rubber laminate top & botttom).
The BDRCs improved dynamics and clarity. Also, reduced that "shrill CD sound" (that's what I call it) on my reference recording with said sound ("Skin" by Beth Hart).
I was lucky to get these used for $38 including shipping.
I've used BDRCs for years. The improvements are unequivocal, even under a 50 pound CD player sitting on an AV Rack filled with sand. Recently, I've switched over to Vibrapod/Vibracones. The improvements over the BDRCs were surprisingly significant. I still have trouble accepting that something so cheap can be so effective.
Do you use the combination of the cones/pods? I have a number some of the pods under my equipment and was contemplating adding the cones. Could you give me any insight on this?