Hey Jim,
I bought a 20' Blue Dragon from Drew at Moon Audio, for my HD-600s. It uses moulded Sennheiser connectors at the earpieces, just like the cruddy, veiled stock cable :-)
I've got about 50 hours on the Blue Dragon, and it's super clean. It was a bit bright at first, settled right down in a few days. Sounds very open, more forward than the stock cable without that darned treble "edge" that I always heard on the stock cable, and blamed on my ears/equipment/age/own stupidity...
I'm enjoying it immensely, and I've given up on trying to solder those damned little Cardas connectors once and for all... <g>
YMMV,
-Don