The MXR Bass Preamp combines a pristine bass preamp with a studio-quality Direct Out in a Phase 90-sized box, providing clear tone without hogging precious pedalboard space. Use it to add a new voice to an old passive bass, sweeten up any amp, or put some special sauce on a particular song. Dial it in just the way you want it and send it straight to the house—pre or post-EQ—with the built-in Direct Out.The Bass Preamp features separate INPUT and OUTPUT level controls and a 3-band EQ section with sweepable midrange—from 250 Hz to 1 kHz—for extensive tonal flexibility. It's all delivered super-clean with high headroom thanks to MXR's Constant Headroom Technology™, and you can use the PRE/POST EQ switch to set whether or not your Direct Out signal is affected by the Bass Preamp's EQ section. And of course, the Bass Preamp features a GROUND LIFT switch in case you encounter ground loop hum.The Bass Preamp is factory preset to operate in 1/4" out buffered bypass and Direct Out active. For players who only want to use the 1/4" out, there are two internal switches that disable the Direct Out and 1/4" out buffered bypass for true 1/4" out bypass mode.MXR M81 Features:Separate Input and Output level controls3-band EQ section with sweepable midrangeStudio-quality Direct Out MXR M81-MXR Bass Preamp Pedal.