Vibrapod Isolators under my speakers?

I'm just messing around and tweaking some. My KEF Reference Twos sit on about a 7" high tile ledge that also holds my other components. I have some Vibrapod Isolators that I was thinking about putting under the KEF's brass feet. Is this better (or overkill) than just having them sit on the brass feet alone? Also, they seem rock solid at loud levels. Should I skip adding any sand or shot to the plinths? The components have Vibrapod Cones underneath them BTW.

Thanks for any input.