> Of course. The switches have three positions: left (voltage is
> subtracted),center (no function), right (voltage is added).
> If the share of the subtracted voltages is higher than the added
> voltages the result is a negative output voltage.

I wonder, if it would be stupid idea not to have +/-1V for every
switch: Perhaps for example +/- 1, 1, 2, 2 volts would be more
versatile (assuming all four switches will have offset function).

Best regards
Jari Jokinen