Samsung md1 Quick Start Manual page 4

Callouts
1. INPUT – 1/4" hi-Z input jack for connecting for instruments or line level signals.
2. THRU – 1/4" output for passing the input signal through to a stage amplifier or monitor system.
3. GROUND LIFT – When the switch is engaged, the input ground (pin-1) is disconnected.
4. BALANCED OUTPUT – Male XLR low-Z connector.
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