1.The receiver can switch between 'Merged(MIX)' and 'Split(AB)' by pressing the power switch button.2.This allows you to record each transmitter onto separate channels on the output ('Split' mode) or combine the two into a single output ('Merged' mode). When it's in 'Split' mode, there will be two output level meters, when it's in 'Merged' mode, there will be just one.