Figured it out. Went on line to ask.com. Put in the question, Why do I get a hum on my surround sound system. Answer was eliminate the sources. Try and disconnect the cable tv from the TV. That was it. Hum went away. Now I can use my satellite system and everything sounds great. I CAN TRY AND GROUND THE CABLE COMING INTO THE RV, but it is not the RV but the cable system at the campground not being grounded properly. Next place might be fine. Keep in mind this is the first time we used this RV, and the first time we use the surround sound system. See what happens at the next campground. But now I know it's a ground problem.