What exactly are you doing with the sound. Is a momentary thing or a what?. I use the exact same card, and use it for cannon sounds or Hit and death sounds triggered by the DBC. You could just run a wire and tie it in to the airsoft fire wire(Blue??) The negative trigger wire must be a shared circuit with the soundd card though. This would mean you would have to have the RX18 and the sound card on the same circuit.