If it wasn't for the sole fact that fiberglass are sold in such big vats I would have tried it already! haha.
May as well dump the rest in my attic for extra insulation...
@jgray: while I don't recall ever having recessed mids relative to bass and trebles when stacking, it made them sibilant IME. Perhaps my ears felt more comfortable but my ear drums shriek in pain after 20 minutes.
Well, one of my headphone still uses stacked pads but no sibiliance there. It's supra-aural though. And kinda uncomfortable.