As Bob Kessler figures it, there will never be enough harmonicas in his collection. “You always have four fewer than you want,” he tells me.

Kessler, who during his 20-plus years of playing has been tutored by blues harp powerhouses Corky Siegel and Howard Levy, is a member of roots band the Black Willoughbys (presently on hiatus) and a solo performer. He’s recently taken an interest in experimenting with looping: stacking the play of one harmonica upon another until it creates a swirling mass of sound. He worked out a solo interpretation of Eden Ahbez’s “Nature Boy” at last year’s Hideout Harmonica Hoedown, bass harmonica included, and is releasing an EP at this year’s edition (Sun 2/16, 7 PM).