The best thing about salons is their ability to seize the moment. Wendy Shuford, folk hostess since 1999, enjoyed her most moving concert with Robin Bullock. The drama of a chance thunderstorm prompted Bullock to ask Shuford to turn off all the lights. Listeners could only see the silhouette of Bullock’s head, the shadows of the trees, and the bright tips of flowers on her balcony as the lightning sparked through the sky. Bullock took up the guitar for his last song—“Shenandoah”—and played thoughtfully, without singing the words. As he finished, the hush remained over the room, as all were too spellbound to speak or clap. That warm, pulsing silence, rare in a concert hall, happens often in intimate chamber music settings.