Just completed this mod and I'm quite satisfied with it. Initially I bought the mini-XLR socket and plug but when they arrived it looked like they are way too big to fit inside this small hole without looking ridiculous. So I went with 3.5mm mini jack option which didn't require much modification in the plastic.
Couple minor issues I've encountered which were not mentioned here:
1. It's quite difficult to fit plastic casing that protects the driver. I've tried putting the cans together without it, but difference in the sound was noticeable, especially on lower frequencies.
2. Locking mechanism that holds the foam in place didn't lock completely on the bottom side as the jack socket pushes whole driver little bit upwards. It's nothing major though.
3. Removing original cable requires you to pull out silver metal thingy :)
Otherwise, it was relatively easy to do and took less than an hour to complete.
Edited by skrobul - 9/11/14 at 5:52am