Drummer Paul Lytton and violinist Philipp Wachsmann are two of the most important and singular figures to emerge from England's free-improv scene. Lytton, a key collaborator with Evan Parker since the late 60s and a longtime member of Barry Guy's London Jazz Composers Orchestra, was one of the first European percussionists to ignore time, but thanks to his early experiences in big bands there's still a propulsive quality to his playing--a dry, often frenetic clatter that ranges across a broad palette of textures. He frequently turns his kit into the drummer's equivalent of a prepared piano, dropping small cymbals and assorted bits of wood and metal onto the drumheads, where he'll strike them or let them bounce. Wachsmann came to improvisation from contemporary classical music, where he mastered extended harmony. In his late-60s group, Yggdrasil, where he performed works by the likes of John Cage, Cornelius Cardew, and Morton Feldman, he began experimenting with contact mikes; since then, electronic manipulation has been a regular feature of his playing, which tends to be more oblique, ghostly, and measured than that of other improvising violinists. Lytton and Wachsmann have worked together extensively over the years, and this rare joint visit, as two-thirds of Ken Vandermark's group Cinc, promises to highlight their rapport. Lytton has played with Vandermark often--he's a member of the reedist's Territory Band, and they released a superb duets collection, English Suites (Wobbly Rail), in 2000. Wachsmann, Lytton, and Vandermark formed Cinc in 2004; on their forthcoming debut album for Okka Disk, the violinist's spectral patterns soften and flesh out his bandmates' sparse, often prickly gestures. Wachsmann and Lytton also play in separate groups tomorrow night at Elastic; see Thursday. Wed 6/7, 9:30 PM, Hideout, 1354 W. Wabansia, 773-227-4433, $8.