STG Sound Labs -largely known for their Moog modular format modules, is fronted by Mr Suit Et Tie Guy - I honestly dont know his real name! We're looking at the .MIX module, a simple 3 channel Audio and or CV mixer module based around the transistor based circuit design of the Moog CP3.
But it's not actually that straightforward, using a bi-polar output pot, the signal can be twisted through 180 degrees, creating a negative or positive result. This is particularly useful when inverting Sawtooth waves or other signals, both for audio processing and CV modulation sources. A nice touch.
As the circuits only use transistors, rather than Op-Amps, as in the are Moog CP3 mixer module, it can also be driven to distortion quite easily, adding extra harmonics.