Thanks to Paul, who is an incredibly patient guy and helped me resurrect my Crack after many years (yes, it sounds incredible, using it now), I am back to hooked on Crack. I own a Denon D2000, a Hifiman 400, and an O2 amp. I am using HD650's with the Crack. It sounds so perfect that I'm tempted to sell my D2000 and HE400, maybe even my O2 amp.
Here's the question... what else runs well with a Crack?! I've looked at Beyer DT880 and 990 in 600ohm, I guess the 770 is no longer offered in 600ohm.
What else is awesome with the crack?! I'm itching!
EDIT: Thoughts on speedball? I may do that soon!