I posted this at TGP earlier this week and only now occurred to me that some people in this forum might find the info useful.
Here is the setup I did with my first attempt;
JMP 2203 speaker out into ps100
QC setup for capturing (guitar into ret 1, capture out to amp, line out from ps100 to input of QC)
and here’s the experiment, line out from the QC back into the line in of the ps100.
I wanted to see if the line in from the QC to the ps100 would make it so I could monitor the capture with a real cab (speaker out from the ps100 to a cab).
It did kinda work, but not accurately. First, the sound that ended up going to the speaker was “hollow” sounding, definitely not right. Second, the signal I was hearing was super gated and kinda fuzzy. I ran the capture anyway just to see. The capture came out sounding like an amp, but not at all like my Marshall. I tweaked the crap out of it until it was kinda close, but I was disappointed.
I decided to try again to see if taking the line out of the QC into the line of the ps100 out of the signal path. It got rid of the “hollow” sound, but signal still had that “gated/fuzzy/yucky” sound. Just for shits and giggles, I turned the ground lift in the QC on and all the sudden, the sound of my amp was there. It was just kinda pure dumb luck that I tried it, really glad I did.
From there I ran the capture process with pretty much no monitoring (did listen with headphones, but with no cab or IR, it isn’t a pleasant sound). It came out great. I’d dare say perfect. I have no idea why the ground loop fixed it, it wasn’t making “ground loop” noise, it was just not sounding right. But… all’s well that ends well.
I started out making a LONG video about all of this to put on YouTube, but I changed my mind and condensed it to this.