I have this Norah Jones' Come Away with me SACD

When playing using my Oppo BDP-80 sending DSD signal to the Onkyo 808, the background have the humming sound like "orooorooooo..." like wind blowing to the microphone, playing stereo version of the SACD got no humming sound.

Then I put the SACD in my 1st gen fat PS3, sending 5.1 LPCM to the Onkyo, the back ground is very clean.

so, is the Oppo having problem or the decoding of DSD by the Onkyo having problem?

I believe the Oppo can be configured to send PCM also. So try that. I'm going to guess it is the Onkyo, DSD is such a difficult format to get right.