Unfortunately, even with today's technology, I have found that there is still channel to channel differences not only in sound but volume as well. It is at its worst with standard definition programming. Also even with HD channels(In my case Rogers is the service provider) I have even found differences in sound and volume from the same network and the same programming. I have all the US networks from both Buffalo AND Seattle. I was watching the game on the weekend and was flipping back and forth between the CBS stations between the two cities and the channel from Buffalo was considerably louder especially in the center channel even though, in both cases, they were broadcasting the same thing. Rogers insists its how they are getting the signal from the origin and it is not them. I think it is probably just a minor change in how the signal is being transmitted down the line and since sibilance is caused by frequencies generally in the 8-10kz range, perhaps a slight tweak to the treble control on your AVR will solve the problem. I doubt it is your speaker.
