For its fifth album, the former Tin Hat Trio is minus one founding member, accordionist Rob Burger, but takes in three new musicians: harpist Zeena Parkins (who has recorded with the group before), clarinetist Ben Goldberg (who has recorded several jazz and klezmer albums under his own name) and multi-instrumentalist Ara Anderson, who contributes a number of horns and keyboards to the mix and has played before with Tom Waits and others.

Despite the personnel shift -- founders Mark Orton (guitar, piano and other instruments) and Carla Kihlstedt (violins, voice and more) remain -- and the wider canvas, the basic M.O.

of Tin Hat remains relatively intact.

The group has been described in the past as "acoustic chamber music," and while that is as apt a tag as any, it's also rather limiting.

Tin Hat draws from a number of not-always-compatible genres -- among them various branches of classical music, world elements and the freeness of jazz -- but then blurs the lines until none are particularly recognizable as such.

But for The Sad Machinery of Spring the reconfigured, largely instrumental group specifically looked for inspiration in the works of surrealist Polish writer Bruno Schulz, who was killed by the Nazis in 1942.

The essence of klezmer and related Eastern European sounds hover over Sad Machinery's compositions and improvisations, but Tin Hat is too unorthodox and resourceful to be so obvious.

There is a balance of many moods and sonic variations among these tracks, ranging from playful and carefree to bucolic to jarringly eccentric.

Whether that reflects Schulz's own creations most listeners will probably never know, but no matter: Sad Machinery is hardly a passive listening experience, but it's never boring.