A high fidelity sound system is designed to deliver excellent audio quality that is clear, detailed and accurate, but there are a few synonyms that can be used to describe this type of technology. For starters, you could refer to a high fidelity sound system as a "hi-fi" system, which is short for "high fidelity." Another term that could be used is "audiophile-grade sound system," which suggests high-quality and precision audio. You could also use the term "expert audio system" or "professional audio system" to emphasize its top-notch sound quality. Additionally, the term "superior sound system" could be used to describe a high fidelity system that delivers an outstanding audio experience.