I contacted asus about a problem with my maximus IV extreme realtek sound. Here is a copy of the email.
"When I first built my computer, I installed windows xp 64 bit because a CAD program that I needed to run was only compatible with Xp. Recently, however, I bought a new CAD program and decided I didn't need xp anymore. I updated to windows 7 64 bit and installed all the newest drivers from the asus site for my maximus IV extreme. For my audio setup I plug in two different speaker sets. each a set of two. One set I plugged in to the green port and the other set into the black port (as per instructions). This was the same setup I used in xp. When I went to play music in Windows Media Player, I noticed that sound was only coming out of the set of speakers i plugged into the green port. I opened the realtek audio configuration, and selected quadraphonic and enabled speaker fill. Now when I play music, it comes out perfectly from one speaker but is garbled, and noisy from the set plugged into the black plug. I switched the speakers in the plugs and whichever was plugged into the black plug was the one that was distorted. With speaker fill disabled, nothing comes out of the black plug speakers. I also tried plugging into different colors but that didn't work with the quadraphonic settings. How can I get it so that high quality sound, or at least undistorted, comes out of both speakers? It worked great in windows xp."
A couple emails back and forth but... no help. Does anyone have any input?
Go into control panel, system and security, system, advanced system settings (on the left column), Hardware tab, Device installation settings, check "no" and "never install driver software from Windows update" save and exit. Unplug your speakers.
Go into device manager and uninstall the Realtek audio. Also make sure to go into Windows update settings and set it to "check for updates but don't download"
Go into your BIOS, and disable onboard audio. Boot into Windows and uninstall the Realtek drivers and delete all the folders. Go back into the BIOS and set the onboard audio to "Auto". Boot into Windows and wait for the onboard audio to reinstall. Reboot and plug in your speakers. Don't update using Windows update. Plug in your speakers and if you did it right, you should be using Microsoft's built in software instead of Realtek.
Sadly, no that did not work. The sound is still distorted in the speaker set that is plugged into the black jack (doesn't matter which set). I followed your procedure twice, and still no avail. Maybe this helps, but when playing a video game it seems like the quad speaker setup works great. If I'm looking at the thing making the noise, it comes out of the front speakers (green jack), if I turn away it comes out of the rear speakers (black jack). There is no distortion. My guess is because the game is setup to be surround sound. So the question is: why is it speaker fill that has the problem? In xp, if I selected speaker fill, the same exact sound would come out of both speakers while I was listening to music, thus giving the illusion of higher quality sound. Why can't I do this in Win 7?