"I dual boot OSX and Windows on my laptop and I have to re-pair the headphones every time I switch OSes. I suspect each OS has a different encryption key, but t

"I dual boot OSX and Windows on my laptop and I have to re-pair the headphones every time I switch OSes. I suspect each OS has a different encryption key, but the headphones can't tell the difference between which OS is running." Your suspicion is correct. The real problem is that Apple and Microsoft both have not provided any way to specify the key to connect with, and they both paired independently, creating a different key each time. One solution would be to find where the link key was stored in one of the OSs and copy it over to the other OS. Then they would both use the same link key and you are good to go until you re-pair for some reason. I don't know if this (still) works, but some instructions are here: https://www.insanelymac.com/forum/topic/268837-dual-boot-bluetooth-pairing-solved/ A different solution could be that the Bluetooth adaptor usually has a way to store the link key within the device in NVRAM. The technicality of that is that the adaptor does never ask the OS for the link key, it just connects. I don't know if tools exist in OSX or Windows to do that, however.