Thanks, Toe. Yes, checking the dynamic-range setting in the Panny was the first thing I did when I noticed the problem, although the first day I wrote about the audio issue in my review, I was perplexed about its cause. It was the next day that David Vaughn and Eddie Feng, two other reviewers, e-mailed me suggesting the problem might be in the Onkyo. Then Ralph confirmed it as well.
And I checked the Panny's dynamic-range setting again after adjusting its output to decode both TrueHD and DTS Master Audio. (The DTS MA 7.1 was also giving the Onkyo fits from a couple of New Line discs, causing a small pop after every return from "Pause." Letting the Panny decode the 7.1 solved that problem, too. Seems the Onkyos have several of these minor glitches, at least the early 605s, 705s, 805s, etc.)