This is interesting... It sounds like the Audyssey system pushed your center channel into breakup by upping the output at certain frequencies.
What does your Onkyo mic look like? The Denon mic that goes with the Denon 3805 (which uses an Audyssey system) is shaped like a flying saucer, and it's about two inches in diameter and 3/4" high. The instructions specify to put it on a tripod at the listening position, but they don't say anything about which way to orient the mic. I'd assumed that it was to be positioned... as a flying saucer would fly, I think that's clear. So am I right or wrong??
AT&T U-Verse Northeast Ohio
Denon x4000, Carver m1.0t, Samsung LED TV, B&W 704 mains, two M&K subwoofers, Oppo 103, Roku 2, etc.
Headphone system: Sennheiser HD600, AKG K702, Hifiman HE-400i, Marantz HD-DAC1 (also used for music playback in the main system, Marantz CD5004, Denon DVD-3910