Hey RG, you could do it with a mixer and midi patches
, e.g. split the guitar signal across all the preamp inputs, return all the preamps to the mixer, run the mixer into the other gear (or use Fx sends/returns) and make a few patches where each preamp is set to what you want for that patch (are al the preamp midi switchable?). Or use 2 mixers, one to send the guitar signal to the preamps (or make Y leads and use the AB switch (does it do A+B as well?) to feed the preamps). IIRC you have a couple of mixers so you could potentially do it this way and have patches that basically zero the preamps you don't want etc. I know this is maybe not quite what you were looking for but you could make it work this way with some fluffing around.Depending on the mixer, if it has channel mutes (like my Behringer UB2442X FX pro which also has 2 x mon sends and 2 x fx sends), I'd run the clean guitar signal into ch1, use Mon sends 1 & 2 to feed 2 x Y leads (provides 4 signals for 4 preamps) but not assign ch1 to any output bus (so you won't hear it), return all preamps to 2 chs each (pan L/R), assign each of these to Fx 1&2 sends to feed your other gadgets (or use subgroups instead but don't send them to the main mix, just use their individual outs), return the other gadgets to chs, then use the ch mutes to turn the preamp returns on/off. I know this is more complicated, but you probably have the stuff to do this already
and you can combine preamps (or not).