A listening bar is a bar whose sound system and record collection are the reason to go. Volume is moderate, the room is treated for sound, and the selector plays for people who are listening — a lineage running from the postwar jazz kissa (jazz coffee houses) through today's audiophile bars.
The form matters in Tokyo more than almost anywhere: cities with small rooms and serious hi-fi culture produced venues where a rotary mixer, valve amplification and horn-loaded speakers are the headline, not the DJ. NUMM in Shibuya sits at the club end of that spectrum, with a custom five-way system and a wood-diffused room; BOSON in Asakusabashi sits at the bar end.
Expect long-form selections, few guest slots, and drinks rather than a dancefloor — though many rooms will happily become one.