Thanks for the thoughts and questions
For mixing, the Pico III has 2 x 3 channel mixers plus a 2 channel mix out.
For attenuation, the Lapsus Os gives me a 4-channel attenuator/attenuverter. Do you think I need more than that?
Good thoughts on the Monsoon and logic. The 0-coast has a simple 2 in-2 out Maths circuit but without any logic.