Helloo, i have " solved this prob i have per accident: Start in Systemcontrol vodoo: left of the millions of sliders is a poti, turn it on 11:00 - and wait a few seconds. The three sliders which are moving on 75 %. after this i have sound - and very good sound. If you have no device,look in the extension folder, in mine there were 2 applehda kext files - all 2 deleted. after this vodoo installed and the above prozedure.