You do not want to draw attention to the sound system, but it must be loud and clear. That'd be silly. In nightclubs, one works closely with the lighting designer to design an integrated system that will send the fearless club-goer into oblivion. But in terms of the sound system, clarity is a key. Bass is also a key.
Clarity is achieved by using good equipment located in good positions.
The addition of several equalizers may further optimize the sound. Bass is achieved by using many subwoofers located in different areas. Tokyo, had a dance floor that vibrates to the music. That's just cool. Bad sound systems seem to be those that tend to emphasize the midrange frequencies.