Nice to know they make a mono/non-stereo-specific one. However looking at the manual it'd still have the same apparent issues mentioned above if not used with a buffer. https://support.lehle.com/en/LEHLE-P-SPLIT-III
They quite possibly mean sending a DI signal from a DAW/interface to an amp...
I had a look at the Lehle P-Split Stereo manual, and I think it won't take care of that buffering issue I mentioned. Here's the manual: https://support.lehle.com/en/LEHLE-P-SPLIT-STEREO
The relevant section is "WHAT IS NOT POSSIBLE" under "Preconditions for Passive Splitting":
So it sounds...
What I've just got working is to run my guitar into my 18i20's instrument input, then out the back at line level into a radial JCR reamp box, into the amp. This works because the 18i20 can function as a mixer and directly connect (as far as I can tell) preamplified inputs to outputs. Maybe your...