a-them mrx 1120/720 Operating Manual page 35

HEADPHONE MUTES PRE-OUTS
If using external amplification, changing this to No allows the speakers continue to
playing while headphones are plugged into the front panel.
MUTE LINE OUT OR DIGITAL OUT
If using a recording device, select the input that the recorder's output is connected to.
This prevents the recorder's output from being fed back to its input, which can result in
a loud noise.
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