The pair's "virtual jazz" bops with the punch of thumb-bumping bass lines, cymbal licks and bongos. The organic electronic soundscape never strays from its taut, almost-delicate arrangements and it never reveals where sampling ends and live instrumentation begins. Koop's computer manipulations spotlight guest vocalists such as Cecilia Stalin, who offers silken crooning on the ethereal title track and the come-hither "Baby." The exuberant Yukimi Nagano's mature-beyond-her-teenage-years singing struts like a trumpet on the brassy "Summer Sun." And her voice lifts the toe-tapping pep of "Sun" and its xylophone solo.
The assured step on Waltz might be off-putting to those needing a trail of electronica breadcrumbs to follow. Unlike Koop's first CD, there are no Portishead or Björk nods; the album unashamedly bathes in '60s-era swing before getting lost in '70s soul once British beat-poet Earl Zinger and legendary jazz vocalist Terry Callier take the helm on the contemplative "Modal Mile" and "In a Heartbeat," respectively. Their self-penned lyrics ensure that Waltz makes you think while you dance -- and forget about the duo behind the computers.
Koop performs at eleven50 Wed., Sept. 10.