Interesting.

I replaced the cabling for mine but they're wired in series (I intend to use them for amateur radio). I used ethernet cable, a TRS plug, and for fabric sleeving I pulled the core out of some olive green paracord.

I've been meaning to make some kind of stylized button to clamp over the Y part but never got around to that.

I have a pair of headphones like these. They have coils that make a thin steel diaphragm vibrate. They were used with crystal radios and vacuum tube receivers, as they have a much higher impedance (takes much less current).

They don't sound great for music, as they were made for telephone or morse code. They don't sound bad for piano music, though.