I have a pair of TX-X00 PH. The H part being the ones with that godawful attached cable. A few weeks ago I spliced into that stock wire and put a pair of 3.5mm jacks inline. It was not much to look at but effective. They had dangly bits:
I beg you not to stare.
Since that was butt ugly I got braver and just today finished installing 2.5mm jacks in the cups:
Required a bit of internal work:
But everything is working and sounding just fine. I won’t go into painstaking details because I don’t know how many out there still have TH-X00 you want to do this too. But if you have one and want help, PM me.