An automated music performance system that is driven by the music-theoretic state descriptors of any musical structure (e.g. a music composition or sound recording). The system can be used with next generation digital audio workstations (DAWs), virtual studio technology (VST) plugins, virtual music instrument libraries, and automated music composition and generation engines, systems and platforms. The automated music performance system generates unique digital performances of pieces of music, using virtual musical instruments created from sampled notes or sounds and/or synthesized notes or sounds. Each virtual music instrument has its own set of music-theoretic state responsive performance rules that are automatically triggered by the music theoretic state descriptors of the music composition or performance to be digitally performed. An automated virtual music instrument (VMI) library selection and performance subsystem is provided for managing the virtual musical instruments during the automated digital music performance process.