I realize this thread is quite old and hasn't been posted in a while, but just in case the OP is still interested...
If there are any other games which play digital audio through the OPL, I would love to hear about them.
Both
Super Fighter and
Sango Fighter support this for all digital audio, with the option to configure the music to play through the Ad Lib at the same time. The digital audio sounds a bit scratchy and it causes some "hiccups" in the music, but it works.
