Guys! I am into maybe 80 hours of burn-in on my HD650s and a remarkable increase in quality has happened. Am I imagining this? We're talking timbre and immediacy rather than soundstage... Gosh, these cans are beautiful. Why did I have to be 60 years old before these beauties arrived on my head? All right. That's a bit gushy. But it's true. IMHO.
+1 They really do open up very nicely
EDIT: If there's anywhere to gush bout the HD650 it's HERE