Hm. Doesn't look like anything out of the ordinary to me from the manual, other than in the troubleshooting guide that says "move it away from the television if experiencing interfernce". Something sounds bust to me.
First thing's first - check that the interconnects work by taking another source like a CD player and plugging it into the CD input of the amp. if that works, it's not the amp or the interconnects.
Then take the interconnects from the "audio out" of the Sony, and plug that in instead. If humming, sounds like the Sony's kaput - there are no options I can see on the Sony that could be muting the output or anything like that........