: Set all gain, level, and EQ knobs to zero (or "unity") before powering on to prevent sudden loud feedback or speaker damage.
: Turn on the mixer first, then any external power amplifiers if used. When shutting down, reverse this order: turn off amplifiers first, then the mixer. audio choice qm4 manual
: Adjust the Gain for each channel until you have a strong signal without clipping (distortion), then use the Master Level to control the overall volume. Troubleshooting and Maintenance : Set all gain, level, and EQ knobs