Problem: You need to add 3 mics to a mixer, which only has one available channel.
Solution: 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.
Specifications
Maximum Gain: +60dB
Input Impedance: 600 ohms
Maximum Input Level: -14dB Maximum Output Level: +14dB
Output Impedance: 600 ohms
Total Harmonic Distortion: 0.02%
Low Cut: -3dB @ 100 Hz
Clip Headroom: 3dB
Output Phantom Power: 12V DC
Power: 12V DC (adapter)/2x9V (batteries)
Dimensions: 5.625" x 3.75" x 1.75"
Weight: 1.5 lbs