DigiTech HARDWIRE HT-2 Owner's Manual page 8

5. Thru Output - Connect this output to the input of your amp or
the input of another pedal if you want the output signal from your
instrument to be audible when the tuner is enabled.
6. Mute Output - Connect this output to the input of your amp or
the input of another pedal if you want the output signal from your
instrument to be muted when the tuner is enabled.
7. Tuning Button - Selects the different tuning references. The tuning
references are labeled below the first 9 LEDs of the Tuning LED Array.
8. DC Adapter Jack - Connect the optional Harman power supply to
this jack. Use the proper supply for your area's mains line voltage.
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