dear italo now i know that i have not undestand a thing.
One thing is sure: i have pictured the dry wet signal exactly like you .Wet signal through 7600 and a stereo amp and then the dry analog signal through a head and then a single cabinet.
Now for the last time to bother you :
if you have a dry analog signal and then an fx signal (in parallel) mixed together (irrespectivelly the type of internal fx routing) then the phasing or latency are a sure thing?
i will dismantle my rig sell it and go for vacations instead.