POWER - Power ON/OFF.
HQ - Oversampling ON / OFF. Use OFF to reduce CPU usage, use ON to get the quality sound without aliases (more CPU). When a project or the track is exported to a wave file (mixdown, bounce, render, freeze) oversampling is always automatically enabled regardless of the position of the button.
GAIN - Determines the amount of gain applied by the Pre Amp.
LOW, MID, SWEEP, HIGH - Tone Stack controls.
POWER AMP - Determines the amount of gain applied by the Power Amp.
VOLUME - Output level.
After Nick_Crow_8505_Lead insert some guitar cabinet emulation.