The sibilance is annoying.
I tried:
A bit of foam from a replacement PX100 pad, also acoustic fabric. No.
Muffles treble but still just as sibilant. Various (4) portable amps, various combinations of mini-cables. Some change it, none eliminate it.
tips: RE0 dual-flange, no change. tri-flange - dark and still sibilant. Comply Tx-400s, less but scatters
(absorbs?) treble, ruins that precise soundstage.
The cord length = fail. I wear them inverted too. I got a
Sleek SA6 52" cable, which is a less substantial cable and not silver-plated, but it's 1' longer and it
does cut down on the sibilance without attenuating treble.
Who knows, better design or increased impedance or magic pixie dust, it fits and it's less sibilant. Also RA connectors give lots more positioning options.
(see pic). The sibilance is not completely gone, but much improved and my player(s) can reach a pocket.