Horizon Devices Apex PreampCABINET Turn the cab sim knob OFF when using a real cabinet. Turn the cab sim ON when going direct or into an interface. GAIN Massive amounts of gain. Start at 0 and turn up until you reach desired saturation. TIGHT SWITCH Engage for more aggressive rhythm tones without adding more gain. Disengage for buttery leads. GATE All the way left completely removes the gate circuit. All the way right gives you a mega tight & modern gate.