+1 on this issue, or at least I think I am.
(I registered today for the sole purpose of adding my voice to this discussion)
Unit is a TSR-7850 purchased from Costco. So at least I know I have a chance at returning it if it ends up being defective even past 90 days (their policy doesn't seem to limit receiver returns to 90 days, at least as far as I can tell).
I'm on the latest firmware (as of this writing) and have reset the receiver to factory defaults a couple of times now in my quest to figure out what was going on.
For me, I only hear the crackling out of the center channel, as if the level is set too high with certain dialog and I get distortion in the audio.
But I would only hear it occasionally, not constantly, mainly when watching programming from my cable provider's DVR. Every time it would happen, which was occasionally, I would cringe, but it would only happen when there was a sudden loudness in the dialog, like it was due to bad sound mixing/too high vocal levels. When there was a lull in the dialog and then someone said something explosive, the levels would cause the dialog to crack/crackle.
I happened to record a movie on the DVR and found a scene where it would happen every time I rewound and watched it, so I knew I had a repeatable situation where I could test with different parameters to see if it was still a problem.
My first thought was maybe that I had a blown a tweeter in my center channel speaker, so I purchased a brand new center channel speaker, and played back the scene from the saved DVR recording. It still cracked, so I knew it wasn't my old center channel (or both center channel speakers were blown, not likely).
Unplugging the center channel speaker and playing back that scene -- no audio crackling/distortion.
It's always a possibility, I guess, that the center channel audio level is coming in too hot from the DVR - maybe only on certain programming? Not sure.
I have used YPAO, so I will try turning it off to see if that makes a difference. There is almost no info online about center channel cracking/distortion so it must not be that wide-spread?
I'm hearing good things about the Denon, so maybe I'll go with that if I can find one!