A high-end, CLASS-A output amp, designed to function as an additional output unit for the L/R master. It provides all routings as well as additional output functions. Installing the AUX master unit to the right of the L/R master unit means that all AUX faders will then go from left to right in numerical order (AUX 1 on the L / R master, AUX 2 and AUX 3 on the AUX master). The unit includes six output amps. Note: All six phone plugs are designed to send balanced signals via space-saving stereo phone plugs. Phone plugs also allow an unbalanced music signal to be connected to any of the outputs via a mono jack. The unit's PFL (pre fade listen) function is similar to that of other mixers. But, as well as being a traditional PFL, this also serves as a fourth AUX send, (without the possibility to independently set levels on channels.) Signals from any input units that have their PFL buttons depressed (red light), will be controlled via the PFL fader and sent to the output via the PFL OUT. (The headphones' PFL functionality is not affected by this fader). AUX 2 and AUX 3 faders control the amount of signal on the AUX 2 OUT and AUX 3 OUT respectively. The unit also includes a talkback section with integrated condenser microphone. Depressing the TB ON button (yellow light) activates the talkback section. The preamplified signal from the microphone can be connected from the TB OUT to any (active) loudspeaker system (in the recording room). Or it can be sent directly to the AUX 2 OUT by depressing the TO AUX 2 button. The correct talkback level can be set using the dedicated VOLUME knob. Headphone section. Headphones are connected to the HP OUT, with the VOLUME knob used to adjust level. Music signals from the L/R master will be heard independently from the signal level determined by the master faders' position. Depressing the PFL to HP button (red light) causes the PFL signal to appear on headphones, provided that the PFL button is depressed on at least one input channel. The control room section is an additional stereo L/R output for driving devices such as room monitors in a recording studio. Other devices can also receive a stereo signal from this output, e.g. a subsidiary PA, side fills, a second recording device etc. The MONO button is useful when listening to a stereo program reproduced in mono, in order to evaluate its "mono compatibility".