It would be a real beast if at least one of the adders were not fixed to octaves but variable within an octave, even better, if both channels had a tiny extra knob for fine tuning 1V/oct
-- luchotron
Sort of like this? https://www.modulargrid.net/e/noise-engineering-quantus-pax-silver You'd have to have some DC offsets to use as your transposition voltages, but this not only handles those individual inputs and mults your primary CV input, there's a circuit that can transpose the entire module's CV complement.