Well, it is something that I have never paid any attention to before, at least. It's not disrupting the listening experience -- it's nigh inaudible, but it still is there, as opposed to how Kleer is marketed as noise-free.
I think it is part of the design. I asked my friend, who also has the 180 phones, to reproduce the sound on his machine, and he said he could hear it as well.
Edited by bluecalx - 4/15/13 at 10:48am