The MX422 is a four channel, microphone/line mixer with balanced XLR inputs and outputs. The unit is ideal for the broadcast and video markets. It has the same features of other ENG / portable mixers without the extremely high price. MX422 FIELD MIXER METER RESPONSE: The meters are set at the factory for a 0 indication of a 0 dbv output level. Non responding meters is caused by only one thing, not enough level from the output amp. To correct this please verify the following. Start with the channel and master at center positions. Make sure the monitor switch is out. 1. Turn up the trim control to the point where the meters read the level you desire. 2. If this causes too much output from the output jacks, push in the attenuator button near the output jacks. 3. Fine tune the level you want with the channel and master controls. Finally, if the Pro standard of 0 dB is too hot for you, there are trim pots for each meter inside the unit that can be adjusted down to a 0 indication of about -10dBv.