Welp

Managed to fix the issue, by unchecking the "Allow applications to take exclusive control of this device" in Sound now allows arma to run perfectly while using my headset at the same time :)

Well mine worked fine up until the 1.05 patch at which point the game would simply crash after going past the splash screens if my USB headset was plugged in at the same time as attempting to run ARMA.

With the vanilla ARMA 2 in order to play I had to unplug my USB headset every time I wanted to play as it would not function otherwise. I am curious as to whether this has been addressed in OA as I am looking to purchase it however if this issue still remains i don't think it will be worth picking up. Thanks.

Most recent beta version again makes no difference to this problem.

I have exactly the same issue with 1.05. Tried going from 1.04 to 1.05 instead and it made no difference.