Insert a ProMIX between the mics and the mixer. Each mic channel on the ProMIX has both phantom power and low-frequency cut selectable via DIP switches plus a level control. The balanced XLR line output can be connected to a mic input on the mixer and headphones or a powered monitor can be connected to the Phone/Aux output. And if AC power is not available, the ProMIX runs on batteries as well. Impedance: 600 Ohm. Dimensions: 143 x 92 x 45 mm. Weight: 680 g.