I made a 75 ohm adapter with a ferrite bead. Now I can only hear hiss with marshmallows past 2:00, which is way too high for listening safely.
Cell phone interference is much reduced. I can only hear it when I'm getting a call or when I'm calling someone. It's actually very useful. I can tell when I'm getting a call, especially if I can't hear anything b/c of my music.