When all bands are set to unity gain, then each band is supposed to be down 3dB at each end of its bandwidth. This will be the frequency which is the geometric mean between the neighboring band. (I believe 3dB means .707 of incoming AC volt level.)
Since the bands are additive, this will result in neutral effect across the spectrum, when all gains are set to unity.
Example, the geometric mean between 125 Hz and 64 Hz (neighboring lower band) is SQRT ( 125 x 64 ) = 89.4 Hz.
So inject a 1V signal at 89.4 Hz.
Set the gain to unity in all bands.
The signal should be .707 V in both the 125 and 64 bands.
You must adjust values so that the Q works out to 1.414, according to the calculator at this link