Several duo and trio sessions along with a couple of quartet dates have been released under the mercurial Chicago Underground moniker, its ever-fluid lineup revolving around the core of Chad Taylor and Rob Mazurek. On this date, the two dispense with nearly all conventions of song structure, instead focusing on angular drum-cornet-vibraphone collages that emphasize clashing dynamics and shifting moods. Taylor's dizzyingly complex polyrhythms boil underneath Mazurek's aggressive horn flights on "Lifelines" and "Memoirs of a Space Traveler" and the marathon blowing of "Two Concepts for the Storage of Light." "Lem" and "Average Assumptions and Misunderstandings," on the other hand, breathe with the space created by Taylor's cascading vibraphone runs and processed guitar. Once again, the members of the Chicago Underground balance the edge between avant-garde jazz and ambient, a crossover they very much helped to create.