he PMBL is a 2 channel passive line level merge box. Each channel has 2 balanced XLR/f inputs. The input signal is merged via a resistor network to a XLR/m output.The top side input is transformer isolated. Possible applications might be the routing of two mixing desks to one power amp or mixing a stereo signal down to mono. Our transformer technology allows for an unbalanced top side input to be sent out balanced.