That can be done but it wold be very complicated to wire it. You would have to have a pressure switch that makes when the sabers are put together or you could just have a switch you turn on when the sabers are together. Then you would have to have a relay in the hilt that will have the sound when seperated and no sound when together, when together the pressure switch or manual switch will make a relay and have the one hilt set up as direct drive or buck puck and when apart the pressure switch or manual switch would be off making the relay swap the LED to use the sound card. Like I said, it can be done but it will be complicated to wire.

EDIT: It wold be a lot easier to have either a slide switch or latching push button switch instead of a pressure switch.