The Tucson Convention Center's Leo Rich Theatre was packed and humming with excitement Wednesday night as the Arizona Friends of Chamber Music premiered a string quartet piece it commissioned from American wunderkind Robert Maggio.

Set to play the piece was the world-class Colorado String Quartet - unusual in the chamber music milieu for being an all-women ensemble.

But the evening began not with music, but with talk, as Maggio strode onto the stage to say a few words about his piece. He proved eloquent, energetic and humorous in discussing his work: Songbook for Annamaria (String Quartet No. 1).

Inspired by both his grandmother (who died just after he received the commission) and his daughter (whom he adopted the same month), the piece proved both a lullaby and a farewell. Maggio built each of its four movements on an American folk song: "Shenandoah," "All the Pretty Little Horses," "Jimmy Crack Corn (Blue Tail Fly)" and "I've Been Working on the Railroad".

Maggio is known for being "gorgeous in sound yet lean in method," and this latest piece embodied those traits. Its spareness was especially notable, heard between Mozart and Dvorák. At times, Maggio's melodic lines were keen and stabbing, piercing the outlines of an old lullaby with fear and angst. At other times, his melodies floated free above whirring harmonies.

The jaunty tip-toe appearance of "Jimmy Crack Corn" in pizzicato amused the audience in the third movement.

In all of the first three movements, the folk songs were at times recognizable. By far the most beautiful and intellectually rewarding part of the piece, however, was the fourth movement, a passacaglia, whose repetitive harmonic motion, Maggio said, was inspired by both the endless demands and the infinite love of fatherhood. Passacaglias combine unchanging harmonies with ever-changing melodic variations. This one unrolled with the relentless swooping of the sea - at times with as hard-driving a work ethic as the railroad song it was based on. In the end, it faded gently into quiet.

In comparison to stereotypes about contemporary classical music, Maggio's work is not uncomfortable; at its best it is indeed lovely. It is by no means easy, however, requiring taut attention throughout.