The Master Output Level control sets the final volume level of the main mix at the software output, before it is sent to the hardware. The output level can be adjusted from -12dB (all the way to the left) to +12dB (all the way to the right). The green, yellow and red audio meter next to the control displays the audio output level after the Master Output Level Control is applied.
Control + click the Master Output Level to reset to 12 o’clock (0dB). When audio is at this level all green segments on the meter are lit. Alt + click the Master Output Level to reset to the +3dB “no headroom” setting. When audio is at this level all green and yellow segments on the meter are lit.
Audio above the +3dB headroom level (i.e. ‘in the red’) will trigger the Serato DJ Pro limiter to avoid clipping, the output audio level will not increase further although the meter will continue to show how much audio is over the limiter threshold by lighting red segments up to +9dB above the 12 o’clock setting. Lit red segments indicate that the limiter is actively affecting your audio, which can degrade the quality of your sound. Keeping the level out of the red is recommended at all times.
NOTE: The Master Output Level works differently in the Offline Player (without hardware connected), and is known there, as Offline Player Volume.