My 2009 review: "The Bop Stop is a music listening room. The managements requests you remain QUIET during all performances." These signs, liberally covering the tables and walls, say it all. The management isn't running a bar that happens to have jazz - they're running the downtown outpost of the Oberlin Conservatory of Music's jazz posse.
The acoustics in the Bop Stop are second-to-none. The whole building was clearly designed for one purpose - listening to fantastic live jazz (primarily instrumental jazz, too.)
2016 update: The director of the Bop Stop wrote me in late 2016 to let me know that in 2014 the facility was donated to the Music Settlement, a community music school. They are now a non-profit club that still showcases jazz, hosting music classes during the day and performances in the evening (complete with liquor permit.)