When playing back music through my apple tv the iTunes volume control is what effects the output level. There is a keyboard shortcut to control this however it is not ideally placed (command+up and command+down). I want to make it controlled buy f5 and f6 which i have done successfully but I have to be in the iTunes window in order for this to function. Is there a way I can have f5 and f6 control the iTunes volume when im not in that window?