Jason from GSG told me this:
⦁ This is the “formula” from the GSG site...
Protective High Filter: 12dB / octave Butterworth @17-20 Hz
Parametric EQ: Freq=20Hz, Q=0.7, Gain=+12dB (will help balance the response from this mid-bass monster).
Overall Level Adjustment: Gain= -12dB
Phase: 180 deg (NX and iNuke amps)
So as you can see, the 'overall gain structure' is set at -12db with a PEQ 20hz boost bringing you to '0' & not the +12db hot you're thinking.