REAR PANEL CONTROLSFUSE:FUSE: 115115 V ~ 15~ 15 AA230 V230 V ~ 8 AX-TREMEMAINS IN AC AC Terminal with integrated fuse compartment for connection to the mains power supply.GROUND LIFT Switch isolates the earth connection from the ground of signal. Should several devices be simultane-ously connected to earth by the same conductor as well as via line connections, a so called hum loopmight appear. In this case operate GROUND LIFT to eliminate the current hum (when pressed).FOOTSWITCH Socket to connect a double latch footswitch with a stereo jack. The tip switches Boost on/off, thering switches the EQ on/off.TUNER OUT Socket for a tuning device. The pure bass signal is available at this socket when the amp is switchedMUTE.LINE OUT Output for connection to an external power stage (post MASTER)EFF. SEND & Sockets to implement the effects loop. Connects the input of the effects to the SEND socket and itsEFF. RETURN output to the RETURN socket.EFFECT MIX control determine the degree to which the effects within the parallel loop affect the signal.DI PRE/POST When this switch is depressed, the signal at the DI OUT socket is the pure bass signal (PRE).Otherwise it is the signal after the tone controls and any connected effects devices have done theirwork (POST)DI OUT Balanced output for the connection to a mixing desk (PA or Studio).SPEAKER OUT Lockable Coaxial Speaker Connection and 1/4" jack socket (only X-TREME 5.1) are connected parallel.