CORRECTION to my observation in posting #4 below.
I consider myself very much a newbie. My first degree is in electrical engineering and while I read a fair bit about audio, I've always been skeptical about cables making much of a difference. I was perusing at a headphone store here in the orient in my travels and built a relationship over three days as I dropped in to take a break. No one was in the store today and so the guy running the store pulled three different cables for the HD650 that I really liked. (It is the old HD650.)
So I tried three cables:
Low cost DIY
High cost custom
He swapped the cables but touched nothing else. When I asked what I was supposed to hear, he said, "Don't let me tell you. You tell yourself what you hear."
The stock has the standard HD650 sound that I've really liked the past few days. The low cost diy (some kind of double purity copper or something) had a smidgen greater clarity which was obvious but wasn't too great a difference. Then the High cost custom just made the HD650 jump in clarity - more torward the HD600/HD598 direction. The difference was huge. I was so sure that this is something I just made up in my mind so I had him put on the standard HD650 cables back. CLEARLY more muffled. The difference was amazing - almost like having a different headphone.
Turn out that customs were his own that is made by a local custom cable maker that makes only cables. We then talked cable and he had Cardas, Zu etc but sold them after he started having cables made by this custom maker.
These cables cost more than the HD650 so that just seem a bit crazy to me as a newbie.
BUT as a first introduction to cable differences, I am now a believer - at least in the part from the headphone to the jack.
Edited by ULUL - 4/19/13 at 8:43am