SumDif is a dual adder/differentiator module capable of handling both CV and audio signals. If you send a 3V signal at the A input and a 1V signal at the B input, then the A+B will output 4V while A-B will output 2V. Numerous applications, like unity mixing, buffering and inverting, can be achieved; you can also experiment with Mid/Side audio processing ! The SumDif has a precision signal path and can process V/oct signals perfectly. The two jumpers on the back side allow to reduce the A+B and A-B outputs gain by 6dB.