NICE BS (no pun)! I like this.shadowdevourer":3swqmb33 said:
Just my little 2¢.
It's a voicing toggle switch specifically designed for Herbert's CH-2 with a (-/+) setting. With the (-) setting selected, blues and classic rock sounds can easily be realized - pick any Marshall amp flavor of your choice. With the (+) setting selected, a more hard rock or common modern rock sound can be realized. The setting (+) slightly re-voices the default CH-2 gain structure so that everything is kicked up a few degrees, but not quite at the gain structure of CH-3. The CH-2 (+) setting also offers more crunch with a good tight low-end bite allowing you to dial in a punchy heavy rhythm sound along with very accurate, articulate and well-defined lead solo tones.
On another not, you also have the option of making the CH-2 (-/+) voicing toggle switch MIDI switchable and programmable which I have myself implemented a long time ago. It really adds a very nice "cheery on top" and in a sense turns the beloved Herbert into a 4-channel MIDI switchable and programmable guitar amp.
If you'd care to dig a little deeper into Peter's tube amp architecture I've provided a link below to a portable document format (pdf) that will give you a brief description of some of the more common elements in his tube amps.
Diezel Tube Amp Service Manual vCore (MAIN)
Good luck!
This could be what I’ve been missing in my life. I’ve always loved Diezel tone but wanted a slightly tighter bottom end. 
