Just a routing idea here, nothing special.
I don't know if anybody is recording guitar (work for bass too) on their MV here.
I wanted to hear my guitar with an MFX (distortion for example) while recording a clear signal, in order to change the sound of the effect as I want afterwards.
I routed the MFX to the master out and my drum and bass tracks to the multi out 1 using the digital out (can use OP1 analog out too if you have).
That let me record the clean signal of my guitar hearing the sound of the effect on it (through the master out) while being able to listen to my drum and bass without changing their sound.
Of course you can also leave the drum and bass (and whatever sound you want) going through the master out and have their sound being affected by the MFX only the time of the recording but in my case I wanted to hear those sounds without effect.