Many thanks to everyone who contributed here, especially you, MI. I knew you'd be able to speak from experience...
No problem. Glad to help.
As I recall, AdLib support in Sierra games under Win 3.1 was inferior to DOS versions and I think the same goes for General Midi support as well
Correct. Win3.x uses its own drivers (by whatever the card manufacturer was) for music instead of the game's own drivers and so the Adlib sounds are not the same. Being that the soundtracks were written with the game drivers and not the Win3.x drivers it would sound better in DOS.
As far as General MIDI goes, though, that depends. If you have a wavetable sound card or an external General MIDI hardware device it'll sound the same whether you play in DOS or Windows. But it all depends on what General MIDI device you have selected in Win3.x.