I figured out how to get 5.1 Surround Sound working in Clear Sky on Windows 7 x64 with Realtek Motherboard Audio. I don't know if this will work with 7.1 Surround Sound, but if it does work please let me know so I can add that it works.

First off this fix requires Realtek 3D SoundBack which is used to restore EAX and Hardware Acceleration. You can download 3D SoundBack <span class="bold">HERE</span>.

Install 3D SoundBack and set the compatibility mode to "Windows Vista (Service Pack 2)" or the program will not launch. Once 3D SoundBack is opened click "Add Game" and name it "STALKER Clear Sky" and for the "Game Path" make sure you select the "bin" folder in your Clear Sky directory. The rest is fine at default settings, click OK. Make sure you click the button "Enable" to properly apply this fix and allow the next step of this fix to work!

With 3D SoundBack enabled and setup, navigate to your Clear Sky "bin" folder. You should see the file "rtk_oal.dll", believe it or not this file is what will properly detect your onboard audio, but it has to be renamed! Delete the "OpenAL32.dll" file and rename "rtk_oal.dll" to "OpenAL32.dll".

At this point you don't need 3D SoundBack enabled anymore so you can choose to disable it for Clear Sky. Leaving 3D SoundBack enabled won't hurt anything either though. The idea of using 3D SoundBack was to get the .dll specific to your hardware which 3D SoundBack generates upon clicking "Enable" for Clear Sky.

That's it! Launch Clear Sky and go to the sound tab, you should see your currently selected audio device in the dropdown list!

Note: Make sure you select your onboard realtek audio for surround sound as the default audio source in your windows sound properties.

Note2: Using this method to enable surround sound may result in crashes upon exiting the game, but is completely harmless.

Reserved.

Topic Stickied. Thanks Judas =)

Thanks for the helpful post. Unfortunately, I use VIA HD Audio and this solution only works for Realtek Audio.
I have found a new solution, which I can confirm works with STALKER.
It's easier than this solution and does not require any installation.
http://indirectsound.com/

Download the package and then extract dsound.dll and dsound.ini to the game installation folder that contains the STALKER executable file. In my case this is : H:\Games\GOG Games\S.T.A.L.K.E.R. Shadow of Chernobyl\bin.
Start the game, go to options and check the sound tab. If you've done it correctly, EAX option should be lit up which means it is enabled.
It also does not crash when you exit the game.

I've just found this solution and tested it on multiple games, it works great.

As themaniacboy mentionde using IndeirectSound is a much easier option. It works for many games and is great help for getting surround sound in older games. Simply copy the "dsound.dll" to the same folder as the program's executable (the .exe file that starts the program/game). The "dsound.ini" is optional but needed if you want to configure IndirectSound to something other than its defaults.

It's basically like the OpenAL Soft procedure. OpenAL Soft could also be used instead of the long method described before.

SImply download OpenALSoft, find the "soft_oal.dll" within it (it has both 32 and 64bit versions within the bin folder) and rename it to "OpenAL32.dll", then place it into the game's executable folder and it will be used instead of the old "OpenAL32.dll" file.

It's always good to back up any files before replacing them.

Also IndirectSound / OpenALSoft don't always work with EAX with every game. Sometimes enabling EAX might cause the game to crash, so it could be worthwhile trying both IndirectSound and OpenALSoft (not at the same time) with whatever game you're trying to restore surround sound in to see which works better with that game.

I actually thought this had all been posted before, strange.