I'm not sure the VOX problem is Card specific.
I have a Santa Cruz Turtle Beach, and I lose VOX for no apparent reason, quite frequently.
Alt-Tab'ing to desktop does not work. Muting and unmuting all sounds does not work, either.
The only fix is to log out of AH, and log back in. It stinks when you lose VOX while flying a 45 min. Bomber sortie in formation on Squad night.
You have no choice but to carry on, deaf.