@cold_fashioned I’m gonna reply to you here 
thread already exists 
Cue 1 is being sent to the Blackbox in my setup (for sampling). I know I could use Bus B for this, but the Cue is more flexible in my experience. I can sample something without having to maintain volume levels between the Bus B and Mains. Also I can send the LMC mic (for piano mostly) to the Blackbox for sampling (and monitoring through headphones). I prefer pre-fader behavior in this setup because, again, I want to control the Blackbox input volume from the SiX, without affecting what I’m hearing in the monitors.
Cue 2 (left) is going into the Matriarch’s instrument input (back through the Bluebox and then into the SiX on a stereo channel). Here, I prefer the pre-fader behavior because I sometimes want to hear only the affected signal, or want to ride the fader of one (original/affected) without changing the other volume.