Does anyone have previous experience building a DOS + Win98 (or 95) machine that allowed both eras of games to be played?
It's actually a pretty common thing. Win9x up to 98SE is built on top of a DOS system and has a pure DOS mode which is compatible with pretty much everything.
The first system mentioned in this thread is the one I've been using for this purpose, for nearly two decades.
With an ISA slot available I'll put a SB16 and be done, it's not the best option quality wise but the combination of compatibility, good enough sound and availability is very hard to beat.
For a single card in a combined DOS/Win9x setup, I'd actually recommend an AWE card unless one is specifically looking for a Yamaha OPL SB16. AWE32/64 support wavetable music in many DOS games (partial list), and General MIDI for DOS games in Windows. AWE64 has slightly better SNR and fewer DSP bugs than earlier SB16/AWE32, but lack genuine Yamaha OPL. "The best of both worlds" can be achieved with an Yamaha OPL (Creative CT1747)-equipped AWE32, but these are rare, and will probably be very expensive.
I'd say - first you should decide whether you want a single sound card for all games or two separate cards (ISA for DOS, PCI for Windows).
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