Recorded in 1976 -- after Brian Eno had proclaimed them one of the best groups around -- but for whatever reason not released until 20 years later, Tracks & Traces is a fascinating release not merely for Eno's participation but for the hints of music that would become mainstream in the future. Indeed, opening cut "Vamos Companeros" has an intense guitar line from Rother that in its nervous, choppy way suggests everything from Wire to Bauhaus, not to mention Eno's own noted production clients, U2. Having already created two excellent albums, the core Harmonia trio was easily placed to whip up a third, with Eno the wild-card factor who turned out to be a perfect addition. While contributing some lyrics and singing at a time when he was steering away firmly from both in his own solo work, most of the time Eno lets the band speak for themselves musically, most notably adding snaky, quietly threatening basslines. Compositions range from the lengthy to just fragments, and while it feels at points more like a collection of sessions than necessarily a complete stand-alone album conceived as such, the end results are still well-worth hearing. The contemplative "By the Riverside," which could easily have turned up on Eno's Before and After Science (where his related collaboration with Cluster, "By This River," appeared) is a slow treasure, a core keyboard loop providing the slow-paced rhythm. "Almost" is another killer, with a lead guitar/piano melody that's pure gentle heartbreak if ever there was such a thing, gently descending and softly surrounded by an elegantly flowing arrangement. If there's less of the glittering glaze of the earlier Harmonia albums, the explorations in ambient sound and mysterious and murky textures make for a more-than-fair exchange.