Just what it says. I've seen some YouTubers playing the DOS version of MM3, and the sound is far superior to what I've had in my game. I can't seem to figure out what settings they use. asking them hasn't gained me any answers. Does anyone know what settings would have the best sound?

Can you give an example?

My bet is they're using a midi synthesizer.

Sure! Here's a link to a streamer I was watching. He says it's DOS, but it could be something vastly different.

https://www.youtube.com/watch?v=mq_dAs1h2P8&t=5021s

I'm not an expert on MM3 (somehow I STILL haven't played it, despite intending to) but you can probably improve things a lot just by running the setup.exe through DOSBox and changing some settings. Check this ancient post for more details:

https://www.gog.com/forum/might_and_magic_series/mm3_poor_sound_and_graphics_compared_to_snes_version/post11

It seems people recommended the Roland Canvas setting for music, whereas the default setting is probably trying to use Soundblaster for music. You should use Soundblaster for digital sound effects, and Roland Canvas for music to get better music.

If you want to get REALLY fancy, you can mess around with soundfonts. This goes above and beyond what the original games used. Basically a soundfont is a set of sounds that your computer can use when playing MIDI music, and you can get some that sound super high quality or that emulate specific sound hardware. If you want to play around with that, I use VirtualMIDISynth (free software) to run soundfonts, and then you can download different soundfonts and try them out. To get those to work, you need to set your game to use General MIDI for music, since soundfonts essentially "replace" general MIDI with better sounding things.

Anyway, hopefully this helps. Note that this only improves the music. For sound effects, I think some type of Soundblaster (original, Pro, 16, AWE32, etc.) is your best bet, you can try different ones in the setup program. Post back if you're still having trouble!