Dave, yes they are soldered not removable unless you re solder it. The original Neutrik plug is reused.
Want to mod them with mini-XLR? I have some extra mini-XLR jacks that you can have, I bough them in bulk since it brought the cost per way down, I was doing 3 headphones with them, 2 T1 and a DT-990 and have 4 extras