I haven't heard an 886, but like you I have spent some time with the 885. The differences between the two are minimal and appear mainly related to new features in the firmware, so I would expect the two Onkyos to sound very similar. Maybe I should try to write down my thoughts on the 885 one of these days - probably not a full review, but at least a little commentary...

I found that the 885 with Audyssey (in a relatively well-behaved acoustical space, albeit not really acoustically treated) was pretty comparable to the 990. Had I gone to the 885 in search of improved sound, that probably would have been a bit of a disappointment. Fortunately, I was just looking for a platform to use for BD player testing that could reasonably match my 990. I felt that the 885 did that, particularly for digital sources.

I came away feeling that Audyssey was not bad, but it didn't really excite me either. THX modes were similar - I used them for a couple months, then found myself shifting back to plain on PLIIx for many things.

I didn't really do a focused head-to-head comparison with multichannel music. I did get a surprise during beta testing of the BDP-83, which I mention in my BDP-83 review . I found that in some cases we preferred the sound of the BDP-83's analog output to the sound of digital output through the 885. That means that even though the BDP-83 has less sophisticated bass management, less flexible speaker delay adjustments, and no room correction software the analog section still sounded better than the 885. It was subtle, and we originally noticed it while switching back and forth on a CD of a pretty good live recording of a piano solo, but it was initially offered as an unsolicited observation from my wife while she was basically ignoring what I was doing at the time.