Digitech XBS Bass Multi-Band Compressor Pedal Level - controls the overall compression level Crossover - selects the frequency at which the signal crosses over from the low band to the high band control. The frequency range runs from 100Hz to 3kHz Low Band - adjusts the amount of low frequency compression plus the output level Dual Outputs. the Amp output is for connecting directly to a bass amplifier. The Mixer output, with CIT bass cabinet emulation technology, is for connecting directly to a mixing board or headphone preamp Level - controls the overall compression level The frequency range runs from 100Hz to 3kHz Low Band - adjusts the amount of low frequency compression plus the output level Dual Outputs. the Amp output is for connecting directly to a bass amplifier. Crossover - selects the frequency at which the signal crosses over from the low band to the high band control. Dual Outputs. the Amp output is for connecting directly to a bass amplifier. The Mixer output, with CIT bass cabinet emulation technology, is for connecting directly to a mixing board or headphone preamp