We present an interactive modular system built in Cycling '74 Max and interfaced with Grame's FAUST for the purpose of analyzing, processing and mapping electrophysiological signals to sound. The system architecture combines an understanding of domain-specific (biophysiological) signal processing techniques with a flexible, modular and user-friendly interface. We explain our design process and decisions towards artistic usability, while maintaining a clear electrophysiological data flow. The system allows users to customize and experiment with different configurations of sensors, signal processing and sound synthesis algorithms, and has been tested in a range of different musical settings from user studies to concerts with a diverse range of musicians. CCS CONCEPTS • Human-centered computing → User studies; • Applied computing → Sound and music computing; Performing arts.