RE: Headphone "upgrade" cables. As a Sennheiser man, I did try the Cardas cable sold specifically as an upgrade for several models, including mine. I tell you the honest truth...I did not hear any difference at all from the factory cable. Not only did I not hear any difference, good or bad, the Cardas cable started shorting out (Rt ear)after 6-8 weeks. They politely sent me another one when I returned the defective product. The 2nd one also shorted out within a month, but at the other end where it plugged into my amp. This time, they just sent me a new 3rd cable and didn't even ask for the 2nd one back. Meanwhile, I ordered another Sennheiser factory cable for $29, instead of the $229 or whatever it was I paid for the Cardas. I get 5 years of good service from the factory cords.

I'm not jogging with these either, as it was my bedroom system consisting of a Marantz CC4001 5-disc changer, into a Musical Fidelity X-24 DAC, then into my Musical Fidleity X-Cans then the Cardas cable to my 580's and 650's.
So to answer your question, it pains me as a "true believer" in cable making a difference; I can't say that the Cardas cable "upgrade" did any good at all for me. All I can say is 3 Cardas "upgrade" cables, no sonic or other benefits- they had sighted 'durability' in their ad, but that certainly wasn't my experience!
KJMAN