A bit of porting effort today, and the ViamSonus class once again compiles under Teensyduino. Example sketch isn't fleshed out yet, and the driver's correct operation isn't yet tested.

The ViamSonus class is a glueball around one instance of the ADG2128 and six DS1881E potentiometers. In the last version, part of that glue's responsibility was to ensure there were no input collisions (which the ADG2128 driver will happily allow). Now the glue should allow mixing.

Also, I've published an example input biasing schematic. Please don't use it until I've run it through more paces. The wipers on the volume control are fairly wimpy, and I want to make certain I can't burn them with a hot signal.