Hi Myles
the most important aspect of the H8000FW internal routing (inputs/DSPs I-Os/outputs)is the configuration of the MAIN inputs and MAIN outputs. Then you can route some of the MAIN inputs to the DSPs, in series or parallel, and get the sound out.
I haven't personally tried using the unit as an audio interface AND an FX processor at the same time. If you accurately report the ROUTING you are using, with each choosen I/O forthe MAINS and the DSPs……we may be able to help.
best
