When using a B&K conditioning amplifier with SoundCheck, it is recommended that the transducer and amplifier settings are configured for unity gain. That way, the level of the signal passing through will be accurately measured by SoundCheck.
To do this, you will need to select Transducer Setup > Sensitivity > Channel 1 > and set this to 0.100V/Pa.
Next, select Amplifier Setup > Out > Channel 1 > and click "+" to change the value to 100mV/Pa.
For detailed instructions including pictures and gain options, please reference the attached pdf.