I just hooked up my Onkyo 875 yesterday and tried to run Audyssey. I have a 5.1 system but everytime Audyssey got the last speaker (surround back right) it gave me an error everytime "speaker detect error"?? I have put the receiver into full stereo mode and all speakers are indeed hooked up. I have asked in a few different forums but nobody has suggested any solutions or why this is happening. Thanks kindly.
See if there's a setting, in the receiver's setup menus, to disable the back speakers. Maybe it's trying to do a 7.1 setup, and you're setup for 5.1? I'm not familiar with that receiver, but I'd see if there's something like that. It sounds like the receiver is expecting to get feedback from those speakers, to compute the setup for them, and they're not there. Just a thought.......... Good luck!