If I swap the GPU's, it reports that the GPU's are in different slots. The NVIDIA card is still "Television: Yes". And if I have only the NVIDIA card installed, and it is in slot 1, then:
My problem is not solved. I suspect that the HDMI Audio 1.1 kernel extension provided here simply does not work with my version of operating system. OS X does not recognize "HDMI Audio" or anything like that. Windows does. Does anyone have a link to the NVIDIA audio kernel extension that I can download? Maybe that, which the HDMI Audio was intended to replace, will work instead.
Optionally, it could be a problem with the Realtek drivers that Apple uses. Realtek has audio drivers updated, but maybe Apple needs to release an update to the Realtek audio drivers that let OS X properly negotiate having HDMI audio (with non-flashed NVIDIA cards) and the Realtek audio (hardware?) simultaneously. Or maybe if me or someone else could build the Linux drivers on the Realtek web site for El Capitan, that might work.
http://www.realtek.com.tw/downloads...=24&Level=4&Conn=3&DownTypeID=3&GetDown=false
When I try to install the linux version, ./configure does not know where to find the kernel. Obviously, it would be Apple's job to go ahead and update their kernel. However, they probably are content... with my inability to have audio in my Mac.
I will now attempt to downgrade to 10.10, to see if this HDMI Audio kext works on that kernel build.