I'll add that not only do they work, they sound great. I haven't found a headphone yet that don't sound good with the S.E.X. (LCD-2, HE-6, HE-500, HE-5LE, HD650, HD800, T50RP, D2000, D5000, D7000, ATH-W3000ANV, TH900). The more sensitive phones had a little background noise, but once the music started, I couldn't hear it. Haven't tried any IEMs with the S.E.X.