Hey Ted, thanks again for such a fast response! Ok I’ve just seen next to the xlr connectors on the back, someone has written on a piece of tape “MON o/p’s 1-gnd 2-L 3-R” so I guess this maybe could be the main output is wired to a single xlr connector with the left channel on pin 2 and right channel in pin 3. I’ll try hooking it up this way and see what happens. 
otherwise perhaps like you said it just uses the group outs, but it seems like there should be a master out since the red fader on the “echo master” module seems to do nothing..
Either way this mixer is awesome! I’m looking forward to getting to know it better !
Best
Zack
