Some time ago I made a sound pack for SMBX and for future projects, using MIDI and OPL FM-Synth chip.
This level I made for create test video
Video demo:
Screenshots & DOWNLOAD THIS LEVEL
Sound pack, used in this video:
Download sound pack
Browse pack's source data (MIDI and WAV)
Note: because is my own sound Pack, I can edit sound and record new. With using MIDI we can do magic
OPL Music:
http://engine.wohlnet.ru/docs/Music/OPL%20Music/
This music - is a rip of playing MIDI files on Sound Blaster 16 sound card with OS Windows 98.