Mark Sandman

Mark Sandman (September 24, 1952 – July 3, 1999) was an American singer singer and bass player of the band Morphine. In Morphine, he played primarily a two-string slide bass guitar. His view was that the song was important, not the instrument and a good song could be played on just one string, let alone four. Sandman collapsed on stage on July 3, 1999 in Italy while performing with Morphine. He was pronounced dead of a heart attack at the age of 46.

It's possible to sound this good playing just two of the strings.