Based on the date it came out, I would bet the ADA MP-1 could be approximated circuit-wise by using whatever Marshall head was in production at that same time period, set input EQ high cut down to 3k or 4k, set most of the tone controls at noon, turning off power amp modeling, using input trim and amp gain as the OD1/OD2 controls, and then using a 3 or 4 band passive output EQ as the ADA tone controls, they were just post gain crappy EQ and didn't do jack squat past +/- 3 clicks...it was just basic marshal circuit in a 1 space rack with synthesizer chorus. That SS clean channel though, you could do that with the compressor block alone, that's spank town.
