Hmm... it looks like the audio circuitry for the OPTi 82C929A was designed with clones like the LS-212 and DSP24S in mind because my 82C929A with a real YMF262 sounds noticeably more distorted than your 82C929A with the DSP24S clone. Have a listen to the attached clip of my 82C929A playing X-Wing's intro. You'll notice the bass notes come out noticeably distorted.
Another thing: it seems the DSP24S outputs louder audio than the YMF262 because I notice that with the same mixer settings as my 82C929A, the FM Synthesis is considerably louder than the digital sound whereas the balance is perfect on my 82C929A.
Also: for the time being, I won't be able to do anything with my 82C929A because I lost all output from the right audio channel of the YMF262. I'll need a new quad op-amp or try to bypass the quad op-amp where it's broken with a dual op-amp taken from a broken Super NES(those use surface-mounted LM358 dual op-amps, which are perfect for attempting to repair my 82C929A).
Wonder how an OPTi 82C930 would sound like compared to the 82C929A. The 82C929A and 82C930 are very similar, but the 82C930 does not require an external audio codec.