I realize this is a massively late reply, but the soundtrack is available for free at Steve Foxon's website:
Sfsounds.co.uk
I totally agree that the story elements of ZODIAC could have been handled better as a stand-alone story; my thought process at the time was to re-use as many of the art assets as possible, but in retrospect I didn't really need original characters from DX.
Fun fact: if you've played Deus Ex: Human Revolution, you may have noticed signs for Foxon Audio. Those *are* a reference to Steve Foxon, who did the music for ZODIAC and some other mods. He knows one of the writers (who has apparently played ZODIAC!).
SteveTack
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