Alright, cables made, REW filters created, and MiniDSP up and running. I had one little issue during hookup, which I didn't have an explanation for until I did a quick update on my sub thread today. Initially I wired the MiniDSP with the input side using the +, - and the jumper from - to shield. I wired the output side using +. -, and shield to the XLR cable connected to the iNuke. But I wasn't geting any signal, just an occasional pop when the MiniDSP cycled something.
Eventually I removed one end of the jumper, and everything seems to work fine, even though I couldn't figure out what had gone wrong. Upon examining this image in passing today, I see that I was only supposed to connect the + and - of the output, and not the shield.
If my way works, is it OK to keep it this way, or should I change it to match the setup above? This way seems to work well with a strong, clean signal, and it got rid of the hum I had been getting with the direct AVR to iNuke setup.