For what little it may be worth to you, I have some experience
in audio and headphones of virtually all types. And I do admit that my experience shouldn't necessarily be relevant to you or anyone else.
I don't pay as much attention to price when gauging what to expect, only to say that we reasonably should expect more when we pay more. The HD600 and HD650 scale very well. Very
well. (In my opinion, of course.) Put world class gear in front of those headphones, and many would agree that they'll give you world class sound. (It's not unusual to see these headphones plugged into some very
expensive amps 'round here, by people who aren't making that headphone choice based on budget, but on performance.) Last year I sold my Grado HP-1. What I sold it for (and what it would cost to buy one) far exceeds the price for the HD 650, but I prefer the HD650 (otherwise I wouldn't have sold the HP-1). Price isn't my main measure. I've heard the L3000 and didn't like it. I've heard the Qualia 010 (and had it here for three months) and didn't like it. Etc. When it comes to headphones, price doesn't tell me much, even though it'd be nice if it was true for all people that we could know for certain that we'd all agree that a headphone that is priced at X*2 will always sound better one priced at X, but that's just not a truth, and I don't think will ever be.
The verdict is
still out. But a handful of very experienced ears have listened to the HD800 (and I will include myself in saying that). It's a special headphone, in my opinion. Really