DigiTech GRUNGE Manual page 8

Connections
The Grunge has a single input (INPUT) and a pair of outputs (AMP and
MIXER). The two outputs give you the following options: running into a
guitar amplifier, running directly to a mixing console or recording device,
or both. The MIXER output uses DigiTech's speaker cabinet emulation
for an authentic guitar amplifier sound without using an amp.
Follow these setup directions before use:
1.Turn the volume down on the amplifier/mixer you are connecting to.
2. Connect the pedal output to the amplifier/mixer input.
3. Connect the guitar to the pedal input.
4. Connect the power supply to the pedal (optional).
5.Turn the level control on the pedal to the minimum position.
6.Turn up your amplifier/mixer level to the desired listening level.
7.Turn on the pedal by pressing the pedal switch and gradually turn up
the level to the desired listening level.