Reading this thread, I thought that this was a bit off the charts, even for me. Well, I tried something of Herbie's that he long longer makes: a 1,1/4" square that is 1/4" thick and harder than his Tenderfoots.
I used them under my Niagara 1200 (no transformer), placed on a bamboo cutting board, which is how I originally had it, with nothing in between.
From what I've read, something as soft as a Tenderfoot would tilt the sound far too downwards so maybe these would do something less offensive.
They did change the sound by fogging up the highs some and putting more emphasis on the mids and bass. I listened intently for over an hour with a few CDs and went back to my normal set up using no kind of footer, which sounded best, between the two set ups, but now I have some doubts as to just what would sound best overall.
Never thought this would happen.
All the best,
Nonoise