Here's another Mad Professor one. Here's the marketing stuff from the Mad Professor website:
"The new Mad Professor - Stone Grey Distortion (SGD) is a modern high-gain distortion pedal with unparallelled clarity and definition.
This pedal was developed for high gain applications and specifically for clarity at heavy distortion levels.
The Stone Grey Distortion is unique in that it has razor sharp dynamics and high gain intensity. It's ready for drop tuning, 7 string, and modern rock players who are seeking extreme gain with intense "string to string definition".
Play a chord and hear each note distinctly, instead of it turning to "mush" like many other high gain pedals.
With the gain turned down, the Stone Grey Distortion approaches overdrive-like textures and responds to the player's touch and dynamics like our other Mad Professor pedals do."
And a demo video too:
Well, it's been taken apart over at freestompboxes.org and here's the schematic (Thanks to RoseBlood11):
As you can see it's quite an interesting setup, with that opamp gain stage pushing a couple of CMOS inverter stages into clipping (they sound good because they've got Mosfets inside:-)
[EDIT] Here's a schematic taken from a 1970's Japanese electronics textbook:
As you can see the structure is very similar but check out the control layout - "bias", "overdrive" and "amplitute", that dual gain control could work quite well. I think this circuit is worth exploring some more, I find I need a little less treble and more bass, I'm also interested in exploring that bias control... If anyone tries it let me know!
Here is his vero to go along with the schematic (Again, RoseBlood11's work):