Preamp Level (Appears Only With Pre-Eq Preamp Signal); Eq Output Level (Appears Only With Post-Eq Preamp Signals); Reverb Output Level - Alesis GT Reference Manual

before being sent to the Output Level Control.

Preamp Level (appears only with Pre-EQ preamp signal)

The display says:
This mixes the preamp output signal into the master effects buss. Note
that this level is dependent on the Preamp Output level found in the
Preamp module.

EQ Output Level (appears only with Post-EQ preamp signals)

The display says:
This mixes the EQÕed signal into the master effects output bus.

Reverb Output Level

The display says:
This mixes the reverberated signal into the master effects output bus.
PREAMP LEVEL:
9 9
EQ OUTPUT LEVEL:
9 9
REVERB LEVEL:
9 9
84