I had a few thoughts going...
1) disconnect the wire between the cups, use two TRS plugs (one for each side) but with only the relevant channels connected - this is probably the easiest option
2) yank out the TRS jacks, put in a mini 4pin XLR
2b) if I could find a TRRS jack... I could possibly rig up a system that could work with both balanced and single ended cables in addition to having the miniXLR, but I think this would depart from the TRRS wiring convension (meh, the more I think of it the less appealing this seems)
3) just hardwire the whole thing
Meh, I should just open it up and see what I've got to work with.
I've also prepared 2 trrs jacks, a braided canare 4s6 and red/blue heatshrink. But then I got another hp, and decided to keep hp50 in stock variant to be sold easier.