Biamp Commercial Audio PREZONE2 20 - 20000 Hz Black20 Hz 20 kHz, Phantom Power (balanced only): +48VDC (7mA input), 3 pin, 0. 3 inch Euroblock, Black Biamp's PREZONE2, a multi functional stereo preamplifier that allows you to independently control the music source selection and volume in 2 stereo zones. It gives you the possibility to mix the 2 microphone levels easily with one of the 4 music sources. The innovative and extremely intuitive design of the front panel will instantly indicate how to