Its been reported that 816M supports 10.8.5 and may fix the sound distortion problem, but others have had to apply the legacy found patch.
I think you mix two separate things: 816M indeed fixed the sound problem but you have to patch audio anyway.
I is needed because the audio chip is not supported by Apple kext as they used unobtainium hardware in their line of products.
The chip used for Quo board is an alternative hardware commonly used by mobo manufacturers, but as it is unsupported OOB by OSX, you have to add support by patching kext or adding an other kext.
For the same reason you could have to add non-Apple kexts to support new hardware that you install on a genuine Mac (printer, TB enclosure with specialized hardware, etc)
No big deal, and not a problem AFAIC.