Most K701 fans will miss the exaggerated soundstage whichever headphone they upgrade to. Having said that, the HE-500 is better in every other aspect. The HE-500s make the K701's seem fuzzy. Take out the grainy treble and mids, and replace it with a nice clean, black background... not to mention the bass is much deeper and more defined on the HE-500s. It also has more of a 3D soundstage, with superior imaging.
Others will probably have better input than this but that were my impressions. I did not have them both side by side for direct comparisons.
Edited by viralcow - 4/23/13 at 6:53am