The experiment in sound that began in 1992, has gone on to beget this fourth outing from the Los Angeles-based duo. It continues to expand and improve upon a seemingly unsurpassable perfect formula that consists of the effervescent voice of Suzanne Perry, complemented by a host of grooves and lazy melodies laid down by guitarist and sonic craftsman Ryan Lum.

"Flux" shows a calculated drift out of their earlier, more traditional, songbird-and-acoustics roots from "Idylls" (1992) and "Ardor" (1994) that once fostered comparisons to such contemporaries as the Cocteau Twins and Lush, and further into the territory that "Ever" (1996) first ventured lightly into.

Alone in the world of breaks and beats, normally inhabited mostly by scores of wannabe DJs littering the d + b scene, Lum is first a musician, but it is served well by his sense of ease with the new medium. Conceived long before Massive Attack's current release, this contribution is far from those high-rent studio theatrics and much more effective.

"Flux" paints a breathier, more elusive picture, conjuring images of love among ruins of a concrete landscape without losing itself in unnecessary flora. While being higher-concept than its counterparts, it remains firmly rooted in the ground. The opening track, "City Moon," plays like a wistful evening spent staring out a vintage high-rise window somewhere, various notes issuing forth from cars and front doors and dogs and pedestrian traffic below.

This is the sort of music that becomes part of a life's soundtrack; it's the record you were listening to when you stayed up all night long doing something important or being with someone, and it made the experience that much more memorable by being part of it.