Patience, patience… 
So… I asked Mattias, who designed the distortion circuit (and much of the analog circuitry in general) - the signal flow is correctly stated in the manual, and the distortion (which is what the symmetry affects) is indeed before the final gain stage.
However, a compressor/final mix stage is naturally dependent on its input - if you send a DC offsetted signal into it, you might hear some DC clicks when adjusting the Level parameter for example. This is completely normal.