Amongst answers to some other questions, here's what the Onkyo "Help" rep said on the topic: "Also AUX2 DIGITAL OUT is fixed at the FRONT DIGITAL or ANALOG outputs there is no way to change that."
I love answers that I can disprove. They give me
so much faith in all other information that I get...
I keep plugging... but wouldn't it be nice if a future version of the Outlaw's 886 Guide addressed the topic of firmware upgrades (what they are and how to do them safely at home).
Good luck on your endeavor. I haven't looked yet to see if the 886 has a firmware update thread at AVS like the 885 did. It was
not a straightforward process on the 885 - made the 990 seem simple.