Sure, it could have been the start of the amp running out of juice. But I thought that clipping usually manifested itself with the bass frequencies giving out. I certainly could be wrong about that. It was the high end that was especially problematic for us, and it wasn't at what I would consider 'reference' levels of volume. Peaks were hitting at about 85db at my listening position.

With my old Elite 43TX that seems to struggle with my M80's, it's the low end that really starts to fall apart when the volume levels are pushed, and that starts to happen at 90+db.

The only two options are 4 ohm and 6+ ohm, so there isn't a discrete 8-ohm speaker setting. I did try the 4 ohm mode, just to see what it would do. It didn't seem to make any difference, either in volume or SQ. And yes, leaving it in 6-ohm mode is also what is recommended over on AVS's 'official' 876 thread.

Likewise, the SC-05 has either a 6 ohm or 8+ ohm setting, which I left in 8+. 4-ohm speakers are not even recommended - they never are with Pioneer. But the SQ is clean and clear all the way out to my volume tolerance level.

M80v2 | VP150v2 | QS8v2
SVS Pci+ 20-39
Emotiva UMC-1 & LPA-1
M22ti + T-Amp, in the Office