I wanted to confirm that under Windows 7 64 I have sucessfully used the rtkhdaud.dat to enable simltaneous analog and digital outputs with realtek dirver 6.0.1.598 . I put it in both the c:\Windows\system32 and C:\Windows\system32\drivers folder as well like many ohers here I have a digital reciever (PCM) as well as multizone analog for other zones in my house. The only problem I have now is that the PCM volume level does not change when I use the volume keys on my keyboard and basically the volume level is locked for PCM connection. I can change the volume in the application ie WMP or iTunes and it goes work. The analog volume control does work. Minor headache because my frineds try to tune up the volume on the keyoboard and it stays the same but the rest of my house is blasting loud. Also mute doesn not work for the PCM connection.
It is stupid that this is not enaabled with out unknow internet dat file. I imagine this is meant to prevent digital to analog copy protectioin but anyone who is going to pirate media is going to use specific software to do it anyway. This just creates problems for poeple who have a legimited use for it.