I had a hum from my Pioneer VSX-D702S. It was particularly to the center speakers but all speakers were effected. I went through a forum topic I had found on Google on the PSAudio website. I went through the motions of looking for a bad capacitor in the receiver, then unplugged all the components and finally looked at the cable receiver. I had a cheap pair of RCA cables, red and white and when I disconnected them from the cable box the hum went away. From there I swapped out the cables to a set that looked much thicker and when I plugged them to the receiver and to the cable box there was no more hum. The cable box has two set of RCA inputs. One is a HD for left and right and the other is a SD with right, left and video. I have a cable that is over ten feet long but it is thick and looks like new. The cable I stuck with has right/left/video and is much thicker than the original cable and it was marked “DISH” so I think I’ll be OK with that. It too is over ten feet long when I need only two feet but I’m not going to buy another cable as long as this one works.
I hope this solution helps someone.