I see thanks.

Thanks so much for this! The General MIDI music sounded so wrong to me. I missed that OPL sound, although it definitely still sounds different from my old Sound Blaster card.
If it's any consolation, there's only speech during the opening sequence. The rest of the game puts dialogue in text. To my knowledge the only way to show subtitles is to get rid of all digital sound entirely.

The music stuttered when i changed the midi device to "4 -1 -1 -1", but changing the prebuffer in dosboxULTIMA1.conf from 10 to 1000 helped. Plays perfectly now.

This old thread just helped me A LOT. I was aiming to run the GOG release of UUW1 on my Android tablet, and at first there was no sound. A little tweaking made speech and sound effects come out, but no music, and that was starting to take too long. This is what made the music come out right off the bat, no more tweaking required in my end. Probably what I needed before this all started, I suppose I didn't need to be tweaking anything had I the original configuration files at hand. I saw this solution elsewhere but in my end I couldn't find INSTALL or UINSTALL files. Checking this thread I ended up finding both UWSOUND and UINSTALL within the CD image, stored in the UW folder I hadn't checked before.

UWSOUND.exe doesn't want to run on Windows 10. What should I do?

You should run it in an emulated DOS environment. You could use DOSBox for that.