How to Do Software Updates: Best Practices It is common problem for most of us that we lose Audio when updating OS X. This is because Apple replaces the AppleHDA.kext with the most recent AppleHDA in the update. The best way to update OS X is via the combo update which is announced by tonymacx86.com or via Apples Combo Update(not via the automatic update). 1. Back up your system. (Friendly reminder: Back up your data any way you can - TonyMacx86) 2. Find the update that refers to you, your OS X and then update via the combo update. 3. Once complete it restarts the system automatically. 4. As a rule when you boot into OS X, functions work correctly but most of the time we have to re-enable Audio. But this isn't true when you only use HDMI. 4. When only using HDMI audio if you have followed this guide ML: UEFI HDMI audio, no dsdt edits then you will not have to update the AppleHDA.Kext. 5. If you are using 2.1/line out/headphones/SPDIF other than HDMI then just apply your preferred method in MultiBeast for your Audio and thats it. You should be good to go. This should be all that you need to apply. Good Luck.