Basically, I need to add the keyboards (stereo mix) and electronic drums (stereo mix/mono if I have to) to an 8 channel PA/mixer and 5 inputs are already taken with vocals. And how about using the submixer for the vocals and send a stereo mix to the main mixer? That leaves 6 channels open........ I'm not PA savvy at all. I can run a good sound mix on a board with a ton of channels though.