 The guitar tech does a basic soundcheck with the different guitars, amplifiers, and effects, to ensure that the equipment is functioning properly and that all of the connections between the equipment (which are made with patch cords) are plugged in correctly.This may be as simple as plugging an electric guitar into an amplifier or plugging an acoustic guitar into a DI box and preamp/equalizer.On the other hand, a tech may have to set up ten or more electric guitars, a variety of amplifiers, and connect them to an intricate sequence of effects pedals.