It's been a great fall for modern music, with Michael Nyman in town, the diverse sounds of the Atelier 90 crowd filling the medieval kostele sv. Vavřince in Malá Strana and the sublime French Institute/Prague Philharmonia series under way again at Švandovo divadlo. But the best is yet to come: the 12th annual Modern Music Marathon.

As always, this year's program features a tasty mix of local and visiting talent. There's a world premiere, two Czech premieres and a reprise of a great Steve Reich piece that, when it's done right, sizzles with the electric energy that lit up late 20th-century American music.

Prague's Agon Orchestra holds court the first night, opening with two pieces by the young Czech composer Marko Ivanoviç. The title of one, Rock's goin' on? suggests the composer's style, a blend of serious and not-so-serious elements.

Then the full orchestra — 30-plus instruments — gets a workout with Symfonie Titan, a brand-new piece by conductor Petr Kofroň. Be forewarned if your ears aren't conditioned to modern sounds: This will be a long sit, at 80 minutes, listening to music that Kofroň has described to band members as "difficult to play and difficult to listen to." As a bonus (of sorts), noted Czech composer Ivan Acher will be sitting in on various electronic instruments to add distortion and other effects.

The second night is the long one, beginning at 6 and ending at midnight for the truly dedicated — or demented. The Agon Orchestra opens the evening with several pieces by its talented keyboard player, Michal Nejtek. Mulling the possible choices, Agon bass player and manager Ivan Bierhanzl mentions one called Thorn Into the Flesh, a virtuoso trio for trombone, cello and percussion. "Let's say we will do this piece," he finally decides with a wicked grin.

The second set should be a real treat: Kiev Kamarata, a chamber music ensemble from the city of Kiev, playing the music of Ukrainian composer Valentin Silvestrov. Well-known in the West, Silvestrov has an intimate, neo-Romantic style seldom heard here.

Conductor-about-town Vojtěch Spurný has assembled a group for the third set, a pair of Reich pieces. Tehillim is a modern treatment of the psalms. Music for Mallet Instruments, Voices and Organ is the centerpiece of the festival, a ringing work loaded with percussion and soaring vocals that was a hit at the Marathon three years ago.

As always, the second night closes on a mellow note, relatively speaking. Locals Ivan Palacký and Filip Cenek will be doing an electronic improvisation based on pre-recorded videotapes. "It's an experimental thing before midnight," says Bierhanzl, which sounds like a fitting coda for an adventurous evening.

But then that's the fun of the Marathons: You never know quite what to expect, outside of a lot of avant-garde musicians pushing interesting boundaries. There's something for every taste and some things that seem beyond taste. It's not for the weak, but it is a musical experience you will not soon forget.