Sorry for a late reply, school work and stuff going on.

As for the issue, the random crashes did stop after that one day, however the headset-unplugging is still causing a crash 100% of the time. It's not a big deal but it's still rather annoying having to relog to game every raid night when I gotta plug in my set.

I've tried changing DirectX9 and 11, with no difference
I've had 3 PCs in the lifespan of FFXIV, and all of them had this headset-problem.
Updating OS/BIOS/Drivers have no effect.
I've used several earplugs, a Razer gaming headset, random storebrand one, and most recently, a Bluetooth set. Each of them have the same results when unplugging (or turning off in case of the Bluetooth one).
I mostly run only Chrome and Discord on background, if any at all. As in case of the most recent PC, I only had XIV on it when I went and tested this issue and it still happened.
I'm only playing on PC and network is Wired. And I usually have no network issues if that helps any.

I don't seem to have this issue on other games, such as WoW, Civilization, etc.