The secret sauce of this is apparently a thin layer (1mm) of PE foam above the PCB, but under EVA foam.
That sounds (pun intended) similar to multi-layered plate padding idea I mentioned before. Great knowing there is at least one combo (1mm + air gap) that works. Thx for mentioning it!
UPDATE: Looks like they are using two layers, 1mm PE foam + thicker foam. Based on some of the videos I watched, one with the combo plate foam and no case foam sounded very distinct and pleasant.
