i love my shure e2c's their kickin, the only issue i have had is when they connect to my 4G 40Gigger, their is a gold contact on the headphone jack that touches the metal casing on the back of the ipod. i seems that the back of the ipod is the ground, and that the gold contact is also ground for the headphone jack. This causes a ground loop. I messed with this in the lab last week, some other guys at work have some 3Gs, we hooked some sensors up and put them on the frequency analizer, and the same noise from the harddrive is apparant on both, but more abundant on the 4G. Their is an easy fix, I just use my ipod remote and the noise is very fant, only if i listen really really close, to i hear it. I am thinking of looking for a headphone cord extension, because i really hate the ipod remote.
But what do I know, I'm just an electrical engineer.