Just to add to the point, after so many years of honestly and truly believing that Zu really transformed my HD650 into something brighter and more detailed, I've decided to run a series of tests against stock cable just to see if there is any significant difference to warrant updating LCD-2 cable.
Shocking and rude awakening. After numerous switching back and forth on the same track I could not pick any difference, same level of details and same brightness with Zu as with stock cable.
Sometimes stock sounded a touch better, sometimes Zu, relistening and scrutinizing the same short passage where I thought I could hear the difference revealed nothing, same exact sound. So mad at myself for being so close minded all these years.