Have you tried Multibeast 4.6.1/ALC892?
MultiBeast 4.6.1 (with my edited DSDT) did not work for me on SL 10.6.8...
...I believe I should take that as a sign that I am wasting both of our time at this point, and I should either upgrade to 10.7 or 10.8 or accept the limitations of my current setup/installation...
So, I guess I wasn't really quite ready to give up and admit 'defeat' just quite yet. And although I'm certainly no pro, I've managed to absorb & retain at least some knowledge during my 3.5 years of hackintoshing. (I have learned to follow instructions much more carefully & precisely, and be even more attentive to detail... if nothing else!)
Anyway, after some scrutiny & comparison of my DSDT with others' successful edits, I felt rather confident that mine was done correctly and that the problem must lie elsewhere. While searching for examples of 'good' DSDTs I was reminded of others who have gotten HDMI & Realtek on-board audio working with/thru their ATI HD 6870s in SL (10.6.8 specifically).
So, I went back and started trying earlier versions of your patched AppleHDA for Lion which are embedded in the archived versions of MultiBeast and I found SUCCESS with your patch of v2.0.2 which I found in MultiBeast 4.4.1.
Two of my displays actually show up as possible audio outputs although only one seems to be working- which is my 42" TV... So that's good! I actually didn't expect the other display to appear in the list- and I'm not even sure if two working HDMI paths are actually possible with OS X or any platform (I don't believe I've ever seen both options in Windows...) I'm also not sure if the audio still functions properly on that display (long, irrelevant story).
The Toslink output works great- haven't had a chance to test its multi-channel encoding (need source media files with multichannel audio & proper player), as well as 3 analog rear outputs! The front mic works beautifully- the input gain/leveling is PERFECT!... I'm assuming the front headphones would also work properly since the adjacent mic input does...
All the gain/output voltage levels are adjusted right in the sweet spot!
SUPERB! You have done a truly outstanding & masterful job of patching the AppleHDA kext... And I know this is not even your latest, most refined & perfected version- but it is the first one I've found that works for my setup- and it's fantastic. Thank you again!
So, to recap:
SUCCESS - "Snow Leopard 10.6.8", "ASUS Sabertooth X58 1402", "Sapphire ATI Radeon HD 6870", "HDMI Audio", "4 displays"
HDMI audio & onboard Realtek ALC892 audio enabled using Toleda's patched AppleHDA (the one found in MultiBeast 4.4.1) plus modified DSDT- edited according to instructions in this thread.
Abbreviated install breakdown:
iBoot + SL Install DVD (copied to high speed USB thumb drive to speed up process since I knew I'd probably end up having to re-install a few times since I often break something early on that's easier to fix with re-installation)
Reboot to new installation with iBoot
Install 10.6.8 Combo update & MultiBeast 3.10.1 User DSDT (nothing selected for audio), install Kext Utility
Reboot
Download & install DSDT editing software, make appropriate edits to DSDT, compile & move DSDT.aml to /Extra, run MultiBeast 4.4.1 selecting Toleda's patched AppleHDA, 3rd party SATA support
Run Kext Utility, then reboot