This is the distortion section from a Vox Super Beatle, which happens to be almost identical to the Colorsound one knob fuzz.   So much so that I used the layout and transistor selection from the D*A*M version.

Interesting when you look at the schematic, as the distortion effect is first in the signal chain, ahead of the preamp.  There's a relay to switch it in and out.  In addition, the circuit is running at 10v, while the rest of the preamp is running at 20v.   So it's very much like an effect pedal in the signal path in front of the amp.

VOX SUPER BEATLE DISTORTION BOOSTER -  0.15" VERO LAYOUT

SCHEMATIC