After all, Fleck is a true pioneer of the five-string, an artist who has not only pushed the stylistic bounds of the instrument itself, but also established it as a stage centerpiece with his effortless rolls, subtle use of harmonics, and single-string runs. Suffice it to say, this 13-track compilation of acoustic duets features all of the above — and in abundance. Fleck is the lone constant; the rotating cast he enlists is the variable that leads him into untrodden turf on each successive track.