I tested the Cardas Clear cable and the CablePro Reverie on my HiFiMan HE500 headphones and to my surprise I have concluded that the upgrade did not make as much of a difference as other cable upgrades. Upgrading to a better power cord (Audience PowerCord E) and a better analog connecting cable (Audioquest Angel) on the amplifier made a noticeable difference in sound quality. Changing the headphone cable was more subtle.
Having grown up with the conventional wisdom that the speaker cables make the most difference among cable upgrades, I was surprised by my findings. For a more complete analysis, see http://donaldscarinci.com/are-headphone-cables-and-speaker-cables-overrated/