So my singer is having way too much fun with his new iPhone and master fader app - playing with levels while I'm trying to sound check, just to wind me up! All harmless fun of course, but am I right in thinking if I want to limit his access on his phone to just his monitor mix, I have to have his phone in my hand and do it on that device? Surely I should be able to limit ALL access to just my iPad via that iPad only? Am I missing something simple here?