I would have to agree with Elberoth as to the difference, as I stated previously, as to the improvement over/to the MK II. That being resolution, which in many cases helps with the dynamics (macro and micro) and frequently better focus in the sound stage. I have only heard the Sig. not in my system, but my feelings were similar to his. Just for the record though, this is not resolution like one would get with an Esoteric, for example. But still greater, noticeably so, than with the MK II.