Let's get this out of the way; I'M A FUCKING NOOB.
I'll add a screenshot in a few minutes after I play around with this some more, but I am attempting to re-amp through my Axe-Fx. I have recorded a direct guitar track through my Firestudio Mobile into Reaper. I set it to play a loop on repeat.
I ran the S/PDIF in and out to and from the FSM to the Axe-Fx (in to out, out to in...) and switched the input in the I/O configs to "Digital Rear." All I get is an insane shriek back through my monitors, in addition to the looped track continuing to play.
The Reaper project is set to 24-bit/48 kHz and is supposed to "force" compliance with that bitrate, so I assume the FSM is doing as it's told. This is the required Axe-Fx clock setting.
Like I said I'm going to keep messing with this, but I'm really hoping to get this working soon. I think it's a matter of signal routing. Do I have to create a "hardware send" from the track?
Even with Reaper closed, I just get that shriek when I switch to Digital input.
Odd thing: I notice that if I'm on a clean patch, the shriek has a different character than a high-gain patch, and if there's reverb or delay... the shriek reverbs or delays.