Oppo UDP205 Audio out on 6/8 RCA Channels to HK 7550HD receiver

I have been trying to figure out how to hear 7.1 audio out from the Oppo through my Harman Karon AVR (HK) 7550 HD receiver.  The Oppo passes the test using their interface, and all speakers work properly. The HK also works properly on setting up the 7.1 speakers using the HK program; It can convert just about any musical source or video, so all 7.2 speakers work properly.  The HK is programmed to bypass its audio processor using the 7.1 inputs.  I am bypassing the HK processor and using the Oppo to provide the audio. The problem  when doing this is I have is I lose the SBR and SBL speakers.   

I am confused about what the 205 actually does through the 6/8 RCA jacks, so many audiophiles state how good the audio is on the 205 using this configuration for playback. I am not sure I have any 7.1 music, or I checked my UHD movies, but they are in 5.1 audio. If I use the HDMI out from the 205 to the HK, all 7 channels work fine. I guess the HK converts most audio signals to 7.1 or 7.2 if you have 2 subs.
  
I retested the 205 on 7.1 setups, and all the speakers worked through the HK, but it drops the SBR and SBL when it is working on the Nvidia, or the Oppo,  frustrating and confusing too... It seems like the Oppo does no conversion of any other audio like Stereo or 5.1 audio to a form of 7.1. If this is true, where can I get lots of 7.1 music?  Or am I limited to 5.1 playbacks on the Oppo!

Thank you
Stewart