The Cygnus Distortion/Sustainer is adapted from the Pete Cornish G-2, a Big Muff-based circuit created in the 1990s for Lou Reed.
Cornish pedals are probably best known for being extremely expensive. There are two reasons for this. First, the build quality and reliability is unmatched. Second, the mysterious nature of them, partially due to the fact that the circuit is obscured and partially because of the A-list of clients. (Along with Lou Reed, the G-2 has also been used by David Gilmour.)
Inside, the circuit is a basic Big Muff with a few changes such as the use of germanium diodes for clipping instead of silicon, and of course the famous class-A transistor buffer design. Both buffers together (the bypass buffer and effect input buffer) have almost as many parts as the main circuit! The classic Big Muff tone control has also been replaced by a standard low-pass filter (treble cut). This creates a significant EQ difference since the tone stack is mostly responsible for the Big Muff’s characteristic scooped midrange.
The Cygnus is a faithful reproduction of the G-2 circuit, but with one major update: an internal switch allowing the pedal to be used in true-bypass mode instead of buffered bypass. As with the Klon KTR, the buffer mode is “almost always better”, but you can be the judge of that.