The Bass BB Preamp distortion booster - Was designed to retain the original attack sound and tonal spectrums and produce a variety of gain structures for all bass players. Each of the two broadly-overlapping EQs - Offers 15dB of Boost or Cut. The gain knob - Offers pristine clean boost to a hard overdriven distortion which is very nice tone that stays firm, with great note separation and just the right amount of compression for a smooth overall texture. True bypass - for eliminating any signal interference when it is switched out.