I recently purchased a 950 to replace an older Rotel preamp, and so far I've been thrilled with it. As I'm now using my home theater much more, I've noticed an odd issue.

Is it possible for there to be dirty pro-logic signals on certain cable broadcasts? I was watching CSI NY today, and I noticed that there was some dialogue leakage into the rear surrounds (more than is customary with pro logic) and that the leaking rear-channel sound would frequently distort. When I switched to the CBS HD channel, the sound on the same broadcast was perfectly clear (still pro logic, but apparently a cleaner audio signal). I've listened to a number of other pro-logic broadcasts since on other channels, and I haven't noticed any steering issue. Is it possible that certain broadcasts simply have lower-quality audio signals, despite them being nominally surround sound sources? And would this affect the pro-logic steering? (Or PLII, to be exact).

Thanks!