King of the Stone Age? Cloning the Limited Edition Mad Professor Stone Grey

Back in February I built the AionFX clone of Mad Professor's Stone Grey Distortion pedal. It was a neat pedal, but the clone wasn't 100% accurate as I ended up using clipping diodes rather than transistors (essentially used as diodes) in the original. I also became aware of a limited edition version of the pedal and figured if I could figure out what changed in that version, it would make a far more interesting build! So, I did something fairly rare, I actually bought a pedal and set about trying to figure out what made it tick.