Designing interactive music systems in Virtual Reality (VR) requires balancing intuitive entry points with expressive depth, yet it remains unclear how domain-specific knowledge (Music Expertise) and medium-specific experience (VR Familiarity) distinctly shape the user experience within these environments. This paper investigates how user expertise impacts engagement with an interactive VR music experience. We conducted a mixed-methods study with 32 participants, categorized by these two factors, to systematically evaluate their influence on perceived usability, immersion, and interaction behavior. Results indicate that Music Expertise significantly enhanced perceived usability, whereas VR Familiarity had no significant effect. Perceived immersion was reported as universally high across all groups, regardless of background. Behavioral data revealed distinct engagement patterns: Experts and VR-familiar users focused more on 6DoF spatial mixing controls, while novices required significantly more time and physical exploration. These findings suggest that for creative VR tools, domain knowledge is a stronger predictor of usability than technical fluency. We discuss the success of a ‘Low Floor, High Ceiling, and Wide Walls’ design and propose critical design implications for onboarding, interaction metaphors, and aligning user intent in embodied music systems.
