Needing Isolation Feet for Bookshelves on Credenza

Hey all,

I'm about to assemble a system that requires my bookshelves sit on a credenza on either size of the TV.  Stands are NOT an option.  Anyone have suggestions on what I can use as 'feet' to isolate speakers better than the little rubber bumpers that come stock?  I'd love something that utilizes spikes as a normal floorstander would allow.