Hi.
The cardas cable has a smoother sound, it's more detailed and faster than the original HD650 cable. It's also a bit bulky when compared to some others. The sound is brighter, leaner, and very different from the dark sound associated with the HD650. The voices of violins tend to sound a bit off/distorted when compared to it though, and i personally didn't like it's performance with classical music-despite it having a better range.
The Equionx cable has the same sound sig as the stock cable: only improved, more refined, and controlled. the bass is excellent. the upper mids sound amazing, their clarity and thickness is especially noted on the Equinox. The treble is also a bit clearer/more defined than the stock.
Blue Dragon: this cable has excellent resolution, more than the Equinox and far far more than the Stock. It is flexible, but sometimes subject to motion noise. The sound sig is dark, and similar to the Equinox. The sound is very deep, wide and balenced. THe frequency response actually levels down quite a bit on the HD650 using this cable: the highs are very present and the bass is controlled.
Silver Dragon- it's suppose to have the highest resolution. It's bright sounding. some, in the past, have expressed quality issues with this cable. It's suppose to be the best dynamic range.
Zu- Havn't heard it, but it's suppose to be bright and much more alive than other cables.
Edit: and yes, sometimes I find myself dancing to my music. the cable is flexible enough for that (blue dragon).