Darkglass Microtubes B7K Bass Overdrive / Preamp Pedal w/ Power Supply and Patch Cables Includes a Power Supply and Patch Cables! Original Design featuring our hybrid FET/CMOS gain stages to provide an amazingly natural tube-like dynamic response Level: Controls the level of the Overdriven Signal Blend: Allows to mix the exact amount of clean signal with the Overdriven. Drive: Sets the amount of preamp Gain.