I called Sennheiser and asked if they had a 1/8" plug cable available for my HD555's. They said part number 528103 was the right cable and that it fit the HD515/HD555. Upon receiving the cable and trying to connect it, the actual connector plug pins fit just fine. But the rubber plug itself that wedges through the opening on the outside of the headphones was a good bit larger than the plug on the original cable. In fact, it was undoubtedly too large to go through. Looking at the opening, one can see a chrome plastic sleeve fitted inside that makes the original opening smaller. Unfortunately, this sleeve is glued/welded to the main plastic housing and cannot be removed. The only option left was to use the dremel to grind out the plastic sleeve.
Being that this is soft plastic, I had to be rather careful. I used a small cone-shaped grinding bit and went around the inside of the sleeve slowly and cautiously for several minutes. I also had to grind out a small bit inside the headphone itself where the top of the rubber plug rests. I used a small brush bit on the dremel bit to clear away the excess plastic.
Unfortunately, the aesthetics aren't absolutely perfect, but only a close examination reveals the modification. The cable did in fact go inside and everything works nicely. But Sennheiser certainly does not need to market the 528103 cable as compatible with the HD555.
If you choose to make this upgrade, take your time grinding. And I would also not recommend it if you ever plan on going back to the original cable as it will probably look like crap.
Being that this is soft plastic, I had to be rather careful. I used a small cone-shaped grinding bit and went around the inside of the sleeve slowly and cautiously for several minutes. I also had to grind out a small bit inside the headphone itself where the top of the rubber plug rests. I used a small brush bit on the dremel bit to clear away the excess plastic.
Unfortunately, the aesthetics aren't absolutely perfect, but only a close examination reveals the modification. The cable did in fact go inside and everything works nicely. But Sennheiser certainly does not need to market the 528103 cable as compatible with the HD555.
If you choose to make this upgrade, take your time grinding. And I would also not recommend it if you ever plan on going back to the original cable as it will probably look like crap.
