I would hope you add audio input headers for PC Speaker and CD-ROM. Will you be able to obtain digital output from the OPL3 chipset via the SPDIF header? Ideally a three input digital mixer should be included for AWE, CD and OPL3.
If you want only take signals from different sources and mix them digitally it is not a problem today already, you can use Live or Audigy.
One benefit to the YMF289 over the YMF262 is that the 289 outputs at 44.1KHz while the 262 outputs at 49.7KHz, The lower sample rate is much more friendly to most S/PDIF inputs than the higher rate.
The main problem is not higher rate but digital format. 262 has proprietary format and it is difficult to make it standard I2S, maybe it's impossible. 289 has a standard I2S.
But the output is not always identical due to the resampling.
🤣 Yesterday you did use dirty noisy analog tracts of regular old ISA cards which bring much more distortions than a good digital processing and you were happy. Nobody said "hey we got not ideally sound processing". And now you want digital mixing/resampling quality and tell about its imperfection. If we use good quality resampling algorithms we get excellent sound quality and no one will hear the difference between the sources and the processed mixed audio output.
hard1k, what about digital output functionality? Will it get WAVE output without limitations? Or you don't know answer yet?