The mountain dulcimer is a deceptively simple-looking instrument. Only about three feet long from tip to tip, with three strings and a neck full of frets, almost like a cross between a violin and ...

When Sam Edelston strolls onstage with a delicate three-string mountain dulcimer, audiences expect him to deliver quaint folk music. “Then I plug in, blast out ‘Smoke on the Water,’ and they go ‘Whoa, ...