The 1920s glamor of the Belasco Theater in downtown Los Angeles provided a stunning setting for a triumphant performance by Mumford & Sons for an upcoming episode of Live from the Artists Den. The band delivered songs from its recent Number One album, Babel, along with such hits as “Little Lion Man” and “I Will Wait.” In a rousing 16-song set, Mumford & Sons thrilled the invitation-only crowd of 800 by stepping in front of the microphones for an unamplified take of “Timshel,” followed later by a joyous cover of Neil Young’s “Dance Dance Dance” before closing the evening with a blistering rendition of “The Cave” from the classic, multi-platinum debut Sigh No More.