It’s amazing, but even when describing an event that promises intimacy and lack of fanfare, pianist Keith Jarrett manages to make it sound sensational. He appears Monday night in Chicago, heading an unusual evening of chamber music highlighted by his own compositions; he promotes it by saying, “If anything, it’s gonna be a lot less dramatic than anyone thinks–which is a positive thing.”

You don’t hear most people touting their work as potentially boring; then again, Jarrett is anything but “most people.” His recorded music includes improvised solo works of concerto length, freewheeling jazz quartet dates, symphonic works, and double albums of solo music on pipe organ and, most recently, clavichord (the particularly engrossing Book of Ways on ECM). He last appeared in Chicago–actually in Evanston, at Northwestern University–at the helm of his “Standards” trio (with bassist Gary Peacock and drummer Jack DeJohnette), a unit that takes its name from their series of albums concentrating on brilliant miniatures of the American popular song tradition. But the “Standards” trio is as different from Jarrett’s earlier jazz excursions as it is from the music to be performed Monday–further proof, for those who still need some, of the pianist’s ferocious refusal to take up residence at any one point on the musical continuum.

For instance, Monday night, in a concert presented by Chamber Music Chicago, Jarrett will be using the chamber ensemble format in a somewhat unusual way, calling upon different members–including clarinetist Richard Stoltzman, cellist Fred Sherry, violinist Lucy Stoltzman, and flutist Paula Robison–to perform in different groupings ranging from solos and duos to the entire ensemble of five. “It’s almost like a repertory company,” Jarrett offered, “except we haven’t been together for a long time.” What’s more, he will present an evening that is purposely unbalanced in an attempt to weave the music from disparate sources into one tapestry. “No one in Chicago has ever seen anything quite like this” is his promise for the evening.

Well, Jarrett has never been one to back away from statements grandiose or controversial.

Sunday’s concert will be a mix of new and old: Bach’s Gamba Sonata in D will open a program featuring two world premieres of Jarrett’s, as well as the Chicago premiere of his Sacred Ground.

The pieces have been selected to work together in making a distinct statement, rather than to provide the balance so eagerly sought by most concert presenters.

“I despise programming,” Jarrett said last week. “Television does that, so you don’t get too much that’s serious or too much that’s light. . . . I think I wanted to de-‘sitcom’ a concert situation by deflating it–by taking away a lot of the possible things that could happen.”

Toward this end, Jarrett has done something most composers would reel at: he has intruded upon the integrity of his own compositions to select out those parts best suited for the larger purpose of his concert. In other words, while Jarrett’s Sonata for Flute and Piano has never before been heard, it still won’t have been heard–at least not in its entirety–after Monday; Jarrett has chosen only the two movements that fit his scaled-down, unexplosive design for the evening.

The result should be a concert woefully without emotional variety, something like a room filled with slightly altered shades of the same color and intensity. Complaints on this subject will roll off the composer’s back. “No one has ever accused Bach’s Tocatta in D Minor of being ‘unbalanced,’ even though it’s all in one key, all in one tempo,” Jarrett declared. “Instead, you keep going further into this man’s space.”

The space Jarrett wishes to explore on Monday is one that will surprise those used to the flamboyance, the thunder and lightning that have always found their place in his piano improvisations and in many of his compositions for orchestra and/or soloist. “It won’t be what many people think of me as being,” he explained. “There won’t be screaming and shouting. The music won’t be all full of different colors every minute. It will show a small line in a space where I often live–and which is not often presented.”

For that reason, the Jarrett pieces will not be improvisations: the space he spoke of can be easily transgressed in the heat of the unplanned moment. “In an improvised concert,” he pointed out, “there’s this rush of substance which is sometimes a very dramatic thing, but not always the best thing. For this concert, I’m trying to reveal what I care about in a less dramatic situation.”

And for that reason, we come back again to Bach, whom Jarrett describes as “a friend for a long time.” Jarrett’s kinship with Bach’s music runs deep–his next project for the ECM label, due in the first part of this year, is a recording of Bach’s Well-Tempered Clavier–and it runs true, for he has successfully delved beneath the veneer of pure logic in Bach’s music to find the sheer emotionality. “I feel Bach is a primal composer, much more so than anyone else. His phrases are music, regardless of what else he does with them. The idea of this concert is that such phrases can stand alone, unornamented; in fact, much of what is heard will sound simple–naive. It may sound simplistic, but it’s alive. . . . That’s why I’m playing the Bach first, because most of the point of this concert has to do with expression through the phrases, rather than through expressivity.”

Keith Jarrett, Richard Stoltzman, and others perform at 8 PM this Monday, December 14, at Orchestra Hall, 220 S. Michigan. Tickets are $6-$35; call Chamber Music Chicago at 242-6237, or the Orchestra Hall box office at 435-8111, for more information.