Hey everyone,
This has dogged me for years, so hopefully this will help some of you.
First up, big kudos to Steven at Neural DSP for this video:
Without that I’d still be dead in the water, and probably still trying to suck that toilet brush piece of software called Audio Meeter (to no avail as usual).
Unfortunately the version of OBS asio he’s using (2.0.3) won’t run in my OBS and the newer version (3.2.1f) that does run doesn’t have the “From Out 1” and “From Out 2” options that his does (sigh) in the video above.
My version only has Input 1 and 2 then USB Outputs 3 through to 8 (from grid).
But, if I change my preset outputs to one of the USB outputs above then I can at least record video and guitar (yay). But without backing tracks, it’s basically guitarcapella which is not much use to anyone 
What I really wanted to be able to do was record video with my playing and a backing track(s) from a DAW (I use Studio One).
The first (semi) successful approach I found was to set my preset outputs to USB 3/4, then add a listen bus in studio one that routed to Out 3+4, then sarifice one of my four tracks on the quad to link Out 3+4 to one of the USB Outputs above that the OBS audio plugin made available to OBS.
So now I had video + guitar + daw but with some pita issues:
- Couldn’t use presets that need all four tracks (i.e. the acoustic sim)
- If I switch presets the backing track cuts out momentarily
(pulls hair)
Aight, so here’s what’s working for me now:
- I plug my guitar into Return 1 (humour me)
- Preset inputs set to Return 1 (well duh)
- Preset outputs to USB 3/4
- Guitar track in Studio One reading from USB Output 3/4
- Main out in Studio One routes to Out 1 + 2 (for my speaker)
- Listen Bus in Studio One routes to Out 3 + 4
- I physically patch OUT 3/L on quad to Input 1
- In OBS, I add an ASIO Input Capture and set OBS Channel 1 & 2 to Input 1
Et voila: Video + guitar + daw with no track sacrifice 
If you’re screaming at the monitor about my guitar going into Return 1, I needed input 1 for the patch and input 2 for my mic (as we all know, any guitar video on youtube has a strict requirement that every 30 seconds of playing must be preceeded by 10 to 15 minutes of disorganized rambling dialogue).
Couple of problems I haven’t been able to solve (help if you can).
Small problem: Can’t audition the factory presets now cos they all use input 1 (not ret1). Guess I could just duplicate them all into a custom bank and tweak the inputs (yeesh).
Bigger problem: I output presets to USB 3/4 so I can mix in the daw relative to the other tracks (Multi Out just blares loudly over everything else). But now I can’t use my quad straight into an amp because all my presets are going (only) to USB (found that out the hard way at an audition).
Sure would be nice Neural if we could globally add and remove routes to Multi Out (hint hint hint).
Anyways, that’s my big dump about that. Hopefully it helps someone. It’s made a huge difference for me when I’m learning songs (I’m working my way through 58 in two months) to make a quick little video after each one just talking about what I’ve figured out (cos by the next morning I’ll have forgotten).