Soundblaster/Adlib has horrible midi emulation, they've never sounded orchestral. If it's supported you should try General Midi instead. Chances are you will actual hear somewhat realistic sounding instruments. (Running the DOS version of GK1 in Windows XP with General Midi selected in the install sounds fine on my laptop).
But as a rule, midi sucks - it's much too platform dependent, which is why not even amateur developers use it anymore. If you keep having problems, try downloading VDMSound, if I remember correctly it has pretty decent General Midi emulation.
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