Sound systems are a type of audio equipment used to amplify sound. They come in a variety of forms, including stereos (7 letters), hifis (5 letters), and parlors (6 letters). Stereos are the most common type of sound system, consisting of two or more speakers and an amplifier. Hifis are more advanced sound systems that use higher quality components and provide better sound quality. Parlors are large, powerful sound systems typically used in public venues such as concert halls and theaters.