Like @PragmaticusMax says having an outboard mixer is a good idea and you can pick up second hand or new mixers pretty cheap online, though its also good to place sub-mixers around your modular to bring some of the parts together. So adding a Matrix Mixer is good as a way to swap and change singal routing before hitting the effects, then post-effects grab a stereo mixer (having the ability to Pan your signals is nice), then the Befaco Output Buss is great to bring all the signals together whether you got for an expernal mixer or not.