Appreciation:
Have, and have had, several cans from most of the majors. Just got my HD800 11 days ago.
My reference system is Lenovo Win7, 8 GB Ram, Foobar2K, JPlay etc. > Ayre QB-9 > Burson HA160DS > HD800 w stock cable.
After over 260 hours nonstop burn-in with them sitting in a drawer, I started listening to favorites from my music collection.
I have a slight problem: I CANT TAKE THE DAMN THINGS OFF MY HEAD!! Nor do I want to. They convey way more pleasurable musical information than anything else I've experienced. Have never heard Stax cans or the HE-6 (I own the HE5LE), but I did audition LCD-3 and they are equally compelling in a very different way. I plan to buy them someday, finances permitting.
Just a couple observations:
The treble "issue" many reviewers speak of, and which was quite present for me, pretty much disappeared after around 200 hours burn-in.
I suspect the low end "issue" (e.g. punch, slam, whambang, etc.) is more related to equipment matching and/or living in a society where explosive base (literally, as in home theater action movie woof-woof) pervades our sonic environment.
To me, HD800 sounds balanced across the frequency spectrum - the base is well defined, dynamically correct, and fast. And vocals are to die for.