I've got a machine with a Radeon 4550 which I recently upgraded to Windows 8 64-bit from Windows XP. I use the card's HDMI output for both video and audio. I used to be able to get surround sound from it in XP, but the sound configuration in Control Panel now only gives me the option for stereo. Upon further inspection, I discovered that this is because the card's sound output is using Microsoft's generic "High Definition Audio Device" driver. I downloaded a program called RadarSync to tell me what driver I should be using, and it informs me that there is a driver version 8.0.0.8808 available for this device from AMD. I have spent the past hour and a half searching AMD's site for this driver, but to no avail. I've also already downloaded and installed the latest Windows 8 drivers for my 4550, but they didn't include the HD Audio Device driver. I'm pretty frustrated at this point. Could somebody PLEASE just tell me were I can get this driver, so I can get my surround sound?!

Installing the Catalyst drivers should install the HDMI audio drivers as well. I wonder what's wrong with your system that it's failed.

Try the driver posted on the Realtek website. It may work.

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CPU: AMD Phenom II X4 810 @ 3250MHz | RAM: Kingmax 2x2GB DDR2 800 @ 833MHz| MoBo: MSI K9A2 CF v1.0 (BIOS: 1.D)| GPU: Asus HD 6850 1024MB (DirectCu) @ 850/1100MHz | Display: Chili Green Vision L24FHD | PSU: PC Power & Cooling Silencer 750 Quad | OS: MS Windows 95 x64 Edition

CPU: Pentium 4 Northwood S478 @ 3200MHz | RAM: 1,5GB DDR 400| MoBo: Gigabyte GA-8S661FXMP-RZ | GPU: Abit Geforce Ti 4200 | Display: Dimarson 19" CRT | PSU: Noname 400W | OS: MS Windows XP Pro, Fedora 18

Edited: 01/17/2013 at 11:18 AM by Eydee

Forcing the RealTek driver caused my system to instantly crash. I found two download links for my card on AMD's site:

http://support.amd.com/us/kbarticles/Pages/catalystlegacywin8.aspx (Windows 8 drivers)

http://support.amd.com/us/gpudownload/windows/legacy/Pages/legacy-radeonaiw-vista64.aspx (Windows 7/Vista drivers)

As you can see, both list the following drivers:
Display Driver
OpenCL(tm)
Integrated Driver
Catalyst Control Center

Note that the HD Audio Driver is NOT on that list. Has ATI just stopped releasing it in the 2000/3000/4000 driver line? Could I get the driver from one of the Catalyst packages for newer cards? Is there a zip file version or something that I could just apply the driver from directly, so I wouldn't have to run the executable for an incompatible driver package?

I figured it out! I'm thinking that everyone who tries to upgrade to Windows 8 from Windows XP and who uses the HDMI port on an ATI card for their surround sound (all 10 of us, in other words) is going to run into this same problem. A number of people building their Windows 8 machines from scratch probably will too. So, in case it benefits anyone, I figured that I'd share what I did:

I searched the folder where Catalyst was installed, and I found the HD audio driver there. The path to it is C:\AMD\AMD_Catalyst_12.6_Legacy_Win8\Packages\Drivers\WDM\HDMICE\W764a\AtihdW76.sys

On close inspection, I noticed that the date of this driver is older than the generic HD Audio Driver that ships with Windows 8. This probably explains why it didn't get installed automatically when I installed Catalyst. However, by going into Device Manager, and right-clicking the HD Audio Device and choosing Update Driver, and then giving it the path to the driver file, I was able to get it to take.

People upgrading from Windows 7/Vista won't run into this problem, because it lets you keep your existing drivers when you do that, but anybody installing Windows 8 on a machine with an older ATI card from XP or from scratch will probably find that they can't get surround sound over HDMI, even after installing Catalyst.

So, if that describes you, now you know what do to!