Once upon a time I did that with a Mozart card, ie. Oak OTI601 + Yamaha OPL3.
There were problems with the native drivers for Windows 9x, eg. MP3 playback in Winamp stuttering.
The solution was to switch the card to WSS mode before starting Windows (MZTMODE WSS), and use the WSS driver provided with Windows.
There was one problem, though - apparently the WSS driver only supports the DAC part, so no MIDI playback via OPL3.
I guess it's possible to solve that problem by installing some other driver for the OPL3 only, but I've never bothered...
Nie tylko, jak widzicie, w tym trudność, że nie zdołacie wejść na moją górę, lecz i w tym, że ja do was cały zejść nie mogę, gdyż schodząc, gubię po drodze to, co miałem donieść.