Hello.
When I installed Yosemite, my audio don't work.
I'll try to install driver of older version of Maveriks as you said in your post, but the problem persists.
Finally, I found the following solución that works for me:
Edit with "vi" this file:
sudo vi /Library/Preferences/SystemConfiguration/com.apple.Boot.plist
Add into the "Kernel Flags" the parameter "kext-dev-mode=1" and let others parameters if exists.
My file looks as follow:
-----------------------------------------------------
?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>Kernel Flags</key>
<string>mbasd=1
kext-dev-mode=1</string>
</dict>
</plist>
-------------------------------------------------------
Save the file, and restart de machine.
When the system start up, enter to Control Panel, select audio, and then the correct device appears. Select the device and enjoy