I listen mostly to classical music, but I'm one that does not find that tuning a system to a particular kind of music is necessary, or even desirable, at least above a certain price point. To me, neutral components produce the best sound (aka realistic compared to live) on classical, jazz, and rock. May be an issue of expectations... I like neutrality over perhaps some narrower emotional or euphonic appeal, not that there is anything wrong with that. I'm just wired to notice accuracy, so I get impatient with colorations of any kind.
I use HD650s, Perreaux SXH1 version 0.5, and very recent 15-foot Cardas cable. Source is a SCD-XA777ES wired via Cardas Neutral Reference and Cross through a passive preamp.
Compared to the stock cable, the Cardas brought out more and better controlled bass and treble, and more detail top to bottom. Until it had well over 200 hours, it sounded bright. Now it is perfect, never bright unless the recording is, and even then quite listenable.
I've heard the Silver Dragon at a meet, and liked it, but it seemed perhaps less dynamic and more emphatic in the midrange. But this was at a meet with lots of cable jostling. I expect that there is much to the idea of moving the cables as little as possible; I've heard this make a big difference in the past on normal interconnects. Also, pros like George Cardas and others have pointed to the phenomenon.
I heard the cables with HD600s also, but I found them just a bit too bright in the treble and recessed in the midrange with any of the cables for me to tolerate.
What I'd like out of my headphone system is another octave of deep rumbling bass. Probably a limitation of the headphones themselves. I get satifying deep bass over the speaker system.
One thing the Cardas have going for them is a good feel while handling. They slide well, coil pretty well, and are not bulky or stiff. They torque freely without getting all into loops.
Also, Cardas company really stands behind their stuff. I had cables from their very early days that developed a discoloration a decade later (sounded OK), and they replaced them all, no questions asked with current, better sounding product.