Summary: I am currently using a loaner pair of HE-500's and thought I'd give my thoughts on the headphones and how they compare to my current pair I was planning on upgrading (Sennhesier HD 600). Keep in mind these are all subjective thoughts, what may be a con for me can be a pro for you based on your preferences. I loaned a pair from The Cable Company, http://www.thecableco.com/Product/NEW-Headphone-Lending-Library.
Summary: I had the opportunity to hear HE-500 under the EU loaner program organized by the EU importer (thank you SievekingSound). I am not really an audiophile (I don’t usually hear critically or do I notice small details in soundstage, etc) but I do enjoy good sound. I have, also, very limited sound experience, both with live music and high end equipment, so please keep this in mind when reading the below and use a fair amount of grain of salt.
Pros: Clear sound, creamy mids, more prominent lows and highs
Summary: The HiFiMan HE-500, practically perfect in every way.
The HE-500 were pretty new territory for me. I have always used Dynamic headphones and was content with them. Then These seductive sirens caught my eye and well....head-fi had it's way with my better judgment and wallet; and by god I'm glad it did! DR.Fang has stuck diamonds and gold with these headphones and has certainly showed me the ways of the Planar Magnetics mystical powers.
Pros: Great sound, Built well, Preformance<Price, Comfort, accesories.