Best option multichannel audio over hdmi for my pc?

I have an Asus M5A97 motherboard with Realtek Azalia HD audio built onto it. Graphics card is Asus EAH6850. Using Onkyo PR-SC886 for pre/pro. Is it possible for me to play Blue Rays with full res HD sound and do 7.1 out in Diablo 3 with this combo?

For some reason the best I've been able to do is ati card stereo sound with this combo. Can't figure out how to get multichannel sound from on board sound chip via the hdmi and would appreciate advice about how to make it work.

I also have an Asus HDAV1.3 slim and have gotten it all working in multichannel PCM mode with that but would rather use the Realtek motherboard sound hardware since it looks like it also supports time alignment per channel and the hdav doesn't

Any tips would be great.. t feels like I must have I tried nearly everything unsuccessfully and am beginning to wonder if it's even possible.

If any one is interested, I ended up shutting off motherboard sound, pulling HDAV out and just using sound hardware on graphics card. I just don't see that any of that other sound hardware buys me anything I need. There isn't all the goofy DSP effect stuff like asus and realtek have built into their drivers but I don't want that stuff anyway. Still haven't figured out the time alignment with the PC thing but my Onkyo will do that so I guess I just have to do some stuff on the onkyo dsp.

The only not quite perfect thing I have come across is 192khz multichannel shared mode sample rate isn't working for me but 96khz 24 bit multichannel is.For all I know it's something wrong with the onkyo not ati's fault. Who knows?

PS haven't tried it yet but has anyone had any luck using windows built in room correction and balancing software? Seems like the ideal way to nail everything all at once if it actually works.