I quite agree, which is effectively what I am doing when using the Xenyx AI for the ASIO Input Capture. Although I can test each “input” individually to get a base setting, when played in realtime, vox/pa, gtr/Pod and Trio/Bass n Drums, its all presented from the Xenyx as a single stereo output. That way I get to see the whole picture. The UMC1820 would give me individual AIC “tracks” in OBS and I would have to guesstimate how the sum of the inputs equates to the single OBS output. The only way to get round that is to then run Youlean in standalone on the desktop, so it picks up the OBS output from the soundcard. ie what is sent to the PC speakers/headphones. That sounds right in theory but yet to test, as I will hit latency issues using the UMC. However, it could be tested with pre-recorded tracks in Reaper and use them as the AIC for OBS. But life is then getting complicated again.
But I could monitor the UMCs dry mix so I am latency free and Youlean run in standalone should get the delayed “wet” PC output. So good enough to monitor maybe ?
Re volume fiddle, was that via the Scarlett ? Seems a bit odd that it would raise the Luffs, so yet another mystery.
After a few weeks off, I need to get back into basic playing before exploring this rabbit hole again. All this can wait and for you too my friend !
Cheers
Toby