The Maxon ST-9 Pro+ Super Tube Pedal stakes a big claim for being one of the most sonically customisable overdrive pedals ever invented. The secret behind this incredible functionality and tone lies in the design which was loosely based on the late 70s OD-808, just with some major upgrades. The Mid Enhance control lets you vary the amount of iconic mid-boost that Maxon overdrives provide, while the Low Boost switch allows a rumbling low-end response with increased saturation thanks to an alternate set of clipping diodes. Add to this, the pedal can operate at either 9V or 18; run at 9V for the classic 808 sound or switch to 18V for increased headroom, improved dynamics, and thicker, chunkier overdriven textures.