I've got mine working:
With Mavericks, I had to keep re-using the kext from multibeast 6.10. I was able to use it with Yosemite, but it was dead after sleeping. The current driver also works but had the same problem after sleep. My solution was similar to those already posted: I had to change my system definition. The ones mentioned above (mac pro 6.1, imac 14.2, etc) didn't work for me.
I found that I had to use Chameleon Wizard, go to SMBios, hit Edit, and select a profile that matched my hardware. When you select a system definition it shows a hardware profile underneath (e.g. Intel Core i5/i7 ivy bridge, Intel Graphics HD 4000). I have a Gigabyte GA-H77N-Wifi using the build-in Intel HD4000 video. It wasn't until I selected a profile that specifically matched the i5 with the HD4000 that my audio began working again after sleep.
If you choose the wrong definition, you can get a kernel panic & will need to boot in safe mode to try another one. Or: It might seem to work but the audio will still quit within a minute after waking from sleep.
TL/DR: The answer is system definition related, the profile you need to use is specific to your hardware; randomly choosing one that's mentioned in the thread probably will not work.