After a year that saw concert venues go dark and stages moved online, an empty storefront in New York has offered a glimmer of hope to artists and audiences ravenous for live music. Musicians across the genres are performing pop-up concerts on Manhattan’s Upper West Side for lucky passersby: on a recent morning it was Beethoven and Debussy that harmonized with a city soundscape normally dominated by car horns, construction work and pigeon coos. It marked the first time Michael Katz, a cellist, was able to play with piano accompaniment in a year; Spencer Myer performed on a white Steinway in an experience he said musicians worldwide have been “starved for.” Perhaps more importantly, the “Musical Storefronts” shows provide an opportunity to interact with an audience, even if they’re watching through a window from the sidewalk instead of seated in any number of the city’s storied halls. “It’s really a reciprocal relationship that we need,” Katz said. “Being able to bring the music to people like we did today is really something unique and special.” The location of performances isn’t broadcast — organizers don’t want large crowds gathering for social-distancing reasons — but the series, which began in late winter, will run through the spring, offering ample opportunity to catch a show. Runners with dogs, parents pushing strollers and elder New Yorkers out for afternoon walks were among the audience members who stopped by for the recent program that also included Mendelssohn and Boulanger. “We’re trying to have some of everything… from classical musicians to people from Broadway, jazz; we’ve had experimental improvisers,” said Kate Sheeran, who directs the Kaufman Music Center behind the series. Along with entertainment, the project aims “to really showcase the artistic engine of New York City, and shed light on the fact that artists need work, and this issue needs attention.”