Nuforce P-9 mass loading

There was a thread here the other day concerning the benefits of using lead weights or some premade product (Bright Star Little rock) on the Nuforce amps. Has anyone tried it on any of the Nuforce pre-amps?

I have both boxes of my P-9 on BDR cones and was wondering whether anyone has found benefit to weighting the tops? How about a shakti stone on the dirty box?