Federico Garcia is beaming: "How is it even conceivable for a group in our position to compose and perform a piano concerto?" He asks the question with a measure of incredulity, as if Alia Musica Pittsburgh's concert had not just taken place Tuesday night at Synod Hall, in front of a buzzing and primarily young audience.

But there are overtones of pride in his voice, as well, revealing the difficulties of what it takes to create a new ensemble and make it through a second season. After all, he is not only a founding composer in the group, but its artistic director and main conductor.

Alia Musica isn't a performing ensemble, per se, but a collective of young, recently graduated Pittsburgh composers that formed in 2006 to bring more local music to the fore and give younger composers a vehicle. Each of the composer members pays a membership fee, which is reduced if they play in one of the concerts. Alia Musica hires the rest of the musicians for the ensembles based on what it programmed.

Hearing their music performed is the best return on the membership fees. But an added benefit is the increased role the composers have in the process, greater than it would be with a symphony orchestra or even string quartet performing their music.

At the concert Tuesday, for example, the piano was out of tune, pitch and ensemble were not always on target and at one point Garcia lost his conducting score. But an authentic, raw joy of music and composition abounded throughout the stage and spilled into the audience. It was a refreshing experience.

"It is a great feeling that we have done all of this ourselves," said Kerrith Livengood, a member and a flutist. Aided by a Seed Award from the Sprout Fund, the group has put on several concerts this year, with some inviting a surprising number of musicians on stage.

The setting of Alia Musica's latest concert, Synod Hall adjacent to St. Paul Cathedral in Oakland, is not a typical space for new music. You are more likely to find the city's early music practitioners, such as Chatham Baroque and the Renaissance & Baroque Society. But Tuesday night actually began with a piece of ancient music -- albeit in new trappings.

Matthew Gillespie's orchestral arrangement of a Vivaldi Concerto in G minor took a great deal of inspiration from Stravinsky. With parts for percussion and voice, and with tiny tweaks in notation, this fascinating piece was akin to putting a new engine in an older car -- it hummed with an energy level it had never had before. The vocal part, sung with a purposefully peculiar manner by soprano Erica Kudisch, worked better in the first and third movements when it was used in moderation. The balance and Garcia's occasionally ambiguous conducting also left something to be desired in the performance.

Garcia then conducted his own piece, "Endecaphony." The work for 11 woodwinds, piano, harp, percussion and string quartet was a marvel. It built from an oscillation of semi-tones to a Ligeti-like cluster, and then gained rhythmic underpinnings that resolved in a woodwind chorale. The subtle piece, which appeared to progress by harmonic and rhythmic shading rather than definite thematic movement, is sophisticated in structure and color.

Mark Fromm's "Lethe" will have some legs. The work for flute, harp and viola imagines souls passing through the mythical underworld river Lethe, whose waters cause permanent forgetfulness. A rare piece whose conception is actually realized in the piece itself, the violist Milda Martisius and flutist Livengood play a melody which they slowly "forget" as time (marked by a constant pulse largely on Julia Scott's harp) goes by. The simplicity and lyricism of the work made it a winner.

The piano concerto that Garcia talked about, James Ogburn's "Proximate Spaces," was a big production indeed, with a chamber orchestra and the honky-tonk piano sharing the stage. Written for Gillespie, who performed it well despite the piano's condition, the soloist's part is of the Brahms Second sort -- hard to play, but not appearing that way to the audience. I couldn't quite grasp the ambitious program in the music, but the episodic work was certainly brimming with musical ideas, styles and rhythms. The most intriguing parts came when the piano soloist's more free-wheeling playing ran up against the more structured music of the rest of the ensemble. But Ogburn's conducting also was not as specific and active enough, and there were numerous ensemble issues.

But for Garcia, it's all a work in progress, and he likes the progress so far, as he wrote in the program notes: "Alia Music is happy -- indeed, amazed -- to make it possible for composers to think big like this."