In anticipation of an incoming CEntrance HifiM8, I decided to switch to a balanced cable for my portable of choice, the Sennheiser Momentum.
Only problem is that there is a TRS 2.5mm jack on only one side, so while making a new cable is a breeze, it wouldn't be balanced. Since I didn't want to risk marring the looks of the Momentums by drilling to each driver, I decided to see what I could do to the jack. I wasn't thinking tutorial, so I only have a couple pictures, but the great news is that the 2.5mm jack is mounted to a PCB that is easily unscrewed from the driver and can be easily de-soldered if you have a solder pump. Once the 2.5mm jack is removed, you have 4 very convenient places to solder the new cable to, including separate grounds (they were joined inside the jack, not on the PCB). All in all, ended up being easier than I thought it was going to be due to the extremely convenient PCB.
Here is a picture of the board with the 2.5mm jack already removed:
Here is the back of the board after soldering wires to it:
Ready to solder the drivers back onto the board (that is hotglue on the board used for strain relief while braiding the cable):
Finished with a mini-XLR: