It's very useful for when you send voiced transmitions out in a cinematic but still allow your player to have control of his units, it basicaly stops other sounds interfering and overlapping your sound transmittion.
Thanks for your advice but would feel better if someone could give me a 100% answer, I k now you have to be careful what triggers to use in a "get local payer" function otherwise it can cause a desync but I just hope setting up volumn channels won;t?