I think you can do this, but I’m not in front of my Qu right now.
Can you “tap” the Mix/Group/Matrix for USB streaming?
I’m considering starting to record “dry” via the Post-Pre direct out to USB on each channel, but also recording the mixes as stems, so that I can perform a live mix during the recording to 2-track, plus stems, via the busses, for a quick rough mix that the band can listen to right away, plus a few stems they can take home to hear their performance in isolation (with perhaps a sub-mix of the rest of the performance 12dB lower, etc.), as well as the usually individual dry tracks for mixing.
For example: Direct outs per channel, as per usual, 1 through 20. USB streaming Count: 20
Mix Outs to USB as mono stems (guitar, guitar, bass, vocals) and stereo via Group Outs (keys, drums, etc.). USB Streaming Count: 28
Main Out as a 2-track stereo mix. USB Streaming Count: 30
Doable?