Boulder Amplifiers 1012 DAC Preamplifier - Manual (Page 23)

MUTE
To temporarily reduce the volume, press the MUTE pushbutton.
“VOLUME MUTED” will show in the display, replacing the volume
indication. Again pressing the MUTE pushbutton will return the volume
to normal level.
While muted, the level of both channels will be reduced by -100 dB,
regardless of volume setting.
OPERATION
2-6