Try AppleALC kext and Lilu. I have exactly the same configuration as yours. No problem with sound. I was also able to configure 5.1 sound for video using combined audio device - works fine with VLC Player. You have to have native not changed AppleHDA.kext and inject audio layout in Clover. I am using 11 layout.
https://github.com/vit9696/AppleALC