This one was kind of a sleeper. No where near as popular as MXR's Distortion +, the Distortion II was quite a bit more complicated and ran off a 15v supply, complete with a built power cord . This layout is a bit modified from the original, and can be run off a normal pedal power supply (+9/18v). Originals also tend to be very bass heavy, so I've included a few mods to tame the low end. You might be able to fit in a 1590B, but a 125B will have a bit more room.