Analog Preamp, Compressor, and Overdrive Delivers classic optical compression tone with a 3-band EQ and PRE/POST selection for enhancing and shaping your bass sound. Features a high-impedance input and XLR balanced output. Incorporates a specially designed Buffer Bypass Circuit to maintain pristine audio quality. Operates with a standard 9V center-negative pedal power supply (not included). Avoid connecting the XLR output to a phantom power source