Herbies Audio Lab states on that site:
“Tenderfoot isolation feet are the stock footers used with Purity Audio Design Statement Series preamps ($19,495-$31,995), Purity Series preamps ($25,995-$52,995), and new PS300B Ultra mono bloc amps.”
I presume they’re using a somewhat-generic name for the PSA BHK 300. Paul, is it correct that Herbies makes the feet for these big amps? I’ve ordered a handful of Big Tall Tenderfoot energy-absorbing feet plus Hi-End Booster Bases for my '250s. Maybe I won’t be using them.