Mac cannot detect external audio driver A little while back I updated my OS to El Capitan 10.11.6. Ever since upgrading from Yosemite the OS has not been able to detect any audio device. In safe mode, it can detect so them and runs no problem has to be a software issue (as identified by apple). I don't want to manually add everything back to a new system to find the issue. 

Any help would be hugely appreciated!
The fact that Safe Mode works suggests that the old drivers for your external audio interface are no longer compatible with the newer OS. Check on the manufacturer's website for a new version, and/or follow any instructions for uninstalling the old driver.

Some audio interfaces are "CoreAudio compliant" and can actually work fine without any additional drivers to those built-in to MacOS. After you've removed the old drivers, it's worth seeing if it will work without installing new ones.