@brotw The shelf is a synthetic composite. Was a one-off isolation rack made by a Japanese company. The only reason I'm using them is because I have them and I may as well put them to use. I also have another one-off carbon-fiber with honeycombed-center shelves, but I don't believe they would support the weight.
I'm sure any isolation shelf / material that you find has been helpful in the past would work.
I've been in touch with Star Sound Technologies (they make the Sistrum and other platforms) to come up with a stable solution for my needs. Their platforms and isolation for speakers are well regarded and they have been a real pleasure to work with. The holdup has been getting a blue-print of the speaker base from Tekton which I hope to have soon.
Another option I'm considering, as a direct comparison to what the Herbie footers have delivered, is IsoAcoustics, specifically their Gaia speaker isolation devices/footers. They are slightly more expensive than my Herbie's solution (16 Gliders) vs 8 IsoAcoustics footers. I'll likely continue using the base shelf + Herbie Gliders with the IsoAcoustics threaded into the speaker base standing on the platform/footers. This will give me another inch of elevation over the current setup.
Other DI owners are happy with Soundocity outriggers, in case you want to explore this option.
