Definition: A "high fidelity sound system" refers to a set of audio equipment designed to reproduce sound very accurately and clearly, without distortion or loss of quality. It is often used for listening to music in a way that sounds as close to the original recording as possible.
In more advanced discussions, you might encounter terms like "audiophile," which refers to someone who is very interested in high-quality sound systems and music. You can also discuss aspects like "soundstage" (the perceived depth and width of sound), "frequency response" (the range of sound frequencies that can be accurately reproduced), and "distortion" (any unwanted changes to the sound).
While there aren’t specific idioms or phrasal verbs directly related to "high fidelity sound system," you might hear phrases like "turn up the volume" (to increase the sound level) or "rock out" (to enjoy music loudly).
A high fidelity sound system is essential for anyone who appreciates music and wants to experience it as intended by the artists.