I have both directv, and Dish in my home currently, and can tell yo u there is a difference between them in pq. Dish has more of a soft picture, and seems to be a bit dull with colors. Directv looks sharper and more vibrant.
This has also been driving me nuts, I too thought of the possibility of blown speakers, but like many of you ruled that out, by connecting other speakers. Sadly, I'm so in tune to this crackle, that I pick up on it all the time now, and don't want to. Also, my wife swears she doesn't notice it at all, so I'm wondering if it's something that not everyone can pick up on!?
Distilled water and microfiber cloth is the best way to clean the screen. As for your cable question, I recently got rid of comcast cable in favor of DirecTV. DirecTV looks a lot better imo, but it really depends on your specific cable company, and how much they compress their service.
It is honestly something I got used to right away with the very first DVD player I purchased. I was actually comparing my old standard vhs tapes to dvds at the time, and marveled at all the stuff I was missing. To each their own, but when I actually watch a bluray that fills my screen, I actually sometimes wonder, ( was this actually filmed in this aspect ratio, or did the company putting out this bluray crop it?)
Bluez3, I too have some clouding, along with some dse issues, but if your set is like mine, then you should be fine. I rarely notice the dse issues, unless I'm looking for them, and the clouding I never notice (with local dimming on) even when looking.
I'm currently moving stuff around with my ht system, and don't have access to internet right now, or I'd.test it. But I can tell you that if you see "super hd" next to the movie or show, then it should work depending on your internet speed.