Warm Audio WA12 500 Series Microphone Preamp Level 1 Designed to transform plain instruments and vocals into exciting tone 2 Meg Ohm True HI-Z input on front panel that sends instrument signal through entire circuit including both Cinemag Transformers and the discrete operational amplifier TONE button switches the input impedance from 600 ohms to 150 ohms; changes the tone of both the mic and HI-Z inputs. High voltage 1731 style operational amplifier 71db of Gain; 48 volt Phantom Power; -20db pad