I apologize for bumping this old thread, but I have not had any success with getting HDMI audio working in El Capitan with my custom SSDT. I am running a Zotac NEN Steam Machine hackintosh. My system is a Skylake i5 (Realtek 892 on board audio) with an NVIDIA GTX 970m 3GB. I have everything working except HDMI audio.
I have attached my system information (ioreg, raw DSDT, config.plist, SSDT.aml). I can't seem to determine if my SSDT is loaded or not. Perhaps I missed a step in my SSDT patches. I tried editing my DSDT with toleda's patches, but unfortunately my compiled DSDT was missing something and I got "still waiting for root device".