I have a 27-inch i7 iMac running 10.6.2 and I can confirm that replacing the kernel extension from 10.5.6 works just fine. I had been having this problem every since 10.6.2 (for some reason it worked up until then). I don't think this fix will work if you are booting with the 64-bit kernel (the default on ALL macs is to boot the 32-bit kernel so you would specifically have to be doing this). I haven't tested it in 64-bit though.
Here are the steps I followed:
1) Download the AppleUSBAudio.kext from 10.5.6 from the following URL.
2) Unzip it.
3) Open up terminal
4) Make a backup of the existing driver by running the following in terminal
cp -Rp /System/Library/Extension/AppleUSBAudio.kext ~/Documents/AppleUSBAudio.kext-BACKUP
5) Exit any applications that are using a USB audio device and unplug all USB audio devices.
6) Unload the existing AppleUSBAudio driver from the kernel by running the below command in terminal.
sudo kextunload /System/Library/Extensions/AppleUSBAudio.kext
If you get an error saying " not found for unload request" your fine. If you get an error claiming it can't be unloaded because its in use (don't have the text in front of me) then stop and go back to step 5.
7) Remove the existing driver by running the following in terminal.
sudo rm -rf /System/Library/Extensions/AppleUSBAudio.kext
8) Put the new driver in place by running the following in terminal.
sudo mv ~/Download/AppleUSBAudio.kext /System/Library/Extensions/AppleUSBAudio.kext
9) Load the new driver by running the following in terminal.
sudo kextload /System/Library/Extensions/AppleUSBAudio.kext
10) Confirm the new driver is loaded by running the following in terminal.
kextstat | grep AppleUSBAudio
The output should look like the folliowing (the 2.5.8b13 is the important bit, some of the other numbers might be slightly different):
cfb@snarfblat:~/> kextstat | grep AppleUSBAudio
141 0 0x96c6f000 0x28000 0x27000 com.apple.driver.AppleUSBAudio (2.5.8b13) <95 94 30 14 8 7 5 4 3 1>
At this point you should be good to go. The only issue with this "fix" is that any time there is an update from Apple there is a chance that the driver will get replaced with a newer one. After each update you should run the command from step 10 again to confirm that you have version 2.5.8.b13. If it gets updated, repeat the above process.
NOTE: Jaycyn I have tried to post this to your WoW forum post of the same issue (
) as that is how I found this thread and the solutions but there is something messed up with my forum account preventing me from posting to the WoW forums.