One of the leading figures in Amsterdam's dynamic jazz scene, Tobias Delius happens to be a terrific clarinetist, but it's the way he plays tenor saxophone that really makes me jump: he combines the breathy, low-register sensuality of Ben Webster, the terse, jagged phrasing of Archie Shepp, and the full-bodied agility of Sonny Rollins in a style that's beholden to no one. Heard in a relatively open-ended setting, as on the eponymous debut of the collective Apa Ini, he demonstrates a brilliant ability to joust and tango with another horn (in this case Hilary Jeffery's trombone), exploring rich contrapuntal improv and extended lines in which the simplest phrases are unspooled into an endless string of permutations. Most of Delius's Chicago appearances, however, have been with the ICP Orchestra, where his on-the-fly impulses are at the mercy of leader/disrupter Misha Mengelberg and a methodology that allows any member to derail the proceedings at any time. A similar free-for-all aesthetic marks the work of Delius's 4tet, a sax-cello-bass-drums outfit operating at a startlingly high level of collective intuition. On its third and most recent album, Pelikanismus (ICP, 2001), the group rolls with telepathic grace from through-composed sections into deeply swinging passages into spazzy freak-outs. Delius played his own tunes here in 2001 backed by some sympathetic locals, but this is the Chicago debut for the 4tet, with Delius, cellist Tristan Honsinger, and the fantastic drummer Han Bennink joined by substitute bassist Valdi Kolli. They'll perform a set and improvise with guests tonight; they'll also play a free all-ages show at 3 PM today at the Claudia Cassidy Theater, Chicago Cultural Center, 78 E. Washington, 312-744-6630. Sun 10/23, 10 PM, Hungry Brain, 2319 W. Belmont, 773-935-2118, donation requested.