Jon,
I'm running a Pioneer DV45a through the coaxial digital output to my Xr45. Although I only use two channels, the default setting was for multi-channel. It seemed to be working because of the rather odd balance coming out of my two mains, like some signal was being sent to non-existent rear and center speakers. Someone with multiple speakers can likely confirm my observation, but I think you'll be fine.
I'm connecting the Pioneer to the Panny with one of the Stereovox HX?? coaxial cables. I like it and others at this site seem to as well. Seems like it isn't even there -- a pretty good trick. Not sure if you can still pick them up for $75, but even at $100 it seems like a good deal. The Panny also accepts optical inputs but, being a bit of a HT dolt, I'm not exactly sure what purpose they serve. Think it has something to do with using DTS or the like on DVDs.
One note, even after about 200 hours of break in and with a non-stock (and non-bright) power cord (run through a decent adaptor), the XR45 is a bit on the fatiguing side after awhile, at least in my nominal Ht set up (the above gear with Von Schweikert VR1s as mains). Could be the DVD player, which only has about 20 hours of CD play on it, but suspect that the XR45 is part of the overall brightness. Your tastes and ears may differ.
Regards,
Chris