How I would love to try the HD800s! Even to get a pair on my ears, let alone plugging in and listening!
After a while of faffing around with my HD600s, I believe I am now very happy with them. As a subjective-nonsense response, I'd say they have a very "hifi" sound, like listening to good speakers a few decades ago, or, indeed, vintage speakers today ---or a few months back was the last time I did--- very rich, sound, perhaps a little bit on the warm side. But hey, they go low, which my previous ATD900s didn't really, so my warmth might be not so much to someone else.
They don't lack detail, but leave me sometimes feeling that I would like more. They certainly have bass, but it wouldn't hurt, perhaps, if it was a little tighter.
Perhaps it just means that I'll never be satisfied, but I think I am ok with the decision that HD800s (or similar cost) would have to wait until my 65th birthday present. There are people who have lived happily with the HD600s for many, many years: I'm sure I can manage three!
My faffing around, by the way, comes under two heads:
--- the passive out[ut on my pre-amp really did not suit. I doubt that they are particularly equipment fussy, but this was a nono. Some impedence stuff I don't understand.
--- I have HF hearing loss, but still have to admit that they sound better without my amateur attempts at EQ, even if that does mean I miss the occasional tinkle or cymbal swish tail.