Nothing beats clay ceramic patio stones with 1'' thick fiber pads made for floor polishers available at the Depot for a few bucks more, topped off with a 1/4" rubber mat. A 17X12 fiber scratch pad will take a lot of weight.
Speaker vibration isolation
P.S. Audio has a video on YouTube, “RMAF 2018”, on Isoacoustic’s speaker vibration eliminator. The demonstration was impressive. Does anyone have experience with these, specifically the ones that replace the spikes as opposed to the stands? Thank you.