I have recently setup an Onkyo 606 receiver with a 5.1 setup. Everything working as expected other than the hissing I get from the rear speakers. I get this when I am connected to Oppo DVD player over HDMI using raw connection. Rear speaker hisses if the incoming signal type does not include support for rear speakers such as stereo. The real strange part is that I also get the hissing when the DVD player showing a static menu of movies on the disk where there is no sound at all. Otherwise when I view anything that has 5.1 support I get either proper sound or no hiss at all from rear speakers. With my prior Pioneer receiver did not have this hissing at all. Anyone experience a similar problem or can provide any ideas how to sort this out?