That is an issue with 7.1 surround sound. The problem is very complicated (I had the lousy Logitech G430 headset with 7.1 fake surround) and it did the same thing the 7.1 razer did, albeit worse.
Try this: turn off 7.1 surround, try again, still broken? Uninstall 7.1 surround and all things affiliated, try again.
If it is still not fixed (often times it won't be) Then we know it has nothing to with Razer's implementation.
My guess: 7.1 drivers are somehow responsible. This is from the fact that when you plug it in/ unplug it, that toggles the problem.
It could also be: windows/razer changing the audio device when the headset is plugged in (e.g. a front panel plug) OBS will not agree with that, and often a stream restart is required.
If you tried the 7.1 drivers removing, and it had no effect, reinstall them (since they do no harm :D) and do this:
plug in headphones
start up OBS
start streaming
get some followers (easiest part :P)
and see if it works IN THAT ORDER
if not, there are other things afoot!
Because i have no clue how nightdev gets his sounds to play, I can't help very much more than windows sound and razer drivers.
EDIT: make sure that OBS's audio input is set to default device!
