
if i understand correct ,,two sets of speakers need to play the master out ,,

and you still want to have monitor function to listen to the mix in your headphones

not possible with the U-Mix Control Pro 2 ,, suggest you use the 1/2 and either y cable connect to the speakers /amp ,,or connect to your amp and seperate it that way ,by either using a line out put off the amp or if the amp can send two sets of speaker outputs
when you get around your set up check the aidio settings especialy the diagram for the output routings ,,
a little bit more info as to the desired set up and equiptment to help with possibilities

oh yeah ,,place the mouse over the gui control for cue mix ,,volume and master and you should be able to adjust thease knobs in the software