I just realized that I had a total misconception of the CONFIG section under the hex tracker. It is so obvious now, I’m not sure why I missed it but it may render some of my previous posts about audio routing partially incorrect.
OUTPUT STRINGS - sends aggregated hex signals to chains (for audio only);
OUTPUT CH1 - sends hex generating device’s CH1 to chains (for audio only);
OUTPUT CH2 - sends hex generating device’s CH2 to chains (for audio only).
So, in my case, the SY-1000 is sending INST 1/2/3 (MODELED GUITARS) out USB CH1 (SUB OUT L) and INST 4 (MAG PICKUP) out USB CH2 (SUB OUT R) over USB. This is why I was hearing aggregated hex audio when a chain was active but with no devices loaded. I just changed it to CH2 and now my DI is getting fed properly to amp sim plugins. I suspect that if you are using the plugin in a DAW with multichannel and an alternative input for CH1/2 that you can probaly now make better use of that, although it might also be useful to have access to stereo input for chains.
I’ll endeavour to update those posts but it’ll take a while. Apologies if I led anybody astray.
FWIW, it might make more sense to label these as “USB CH1 to CHAINS” and “USB CH2 to CHAINS” – or something like that. I think I had it in my head that it was to do with MIDI output channel config and that it wasn’t functioning properly yet.