Several mini-festivals have been layered into the larger framework of this year's Aspen Music Festival, the most recent being a week long focus on the composer Robert Schumann. To the festival's credit, the programmers avoided the obvious compilation of the composer's greatest hits, instead going for a mix of familiar and unfamiliar works.

Alas, as it turns out, those lesser known works are obscure for a pretty good reason. At least for me, after the desultory performances they got on the first half of a couple of concerts exploring Schumann's music for piano and strings, the better known quartet on the first program and the quintet on the second evening arrived as a huge relief.

Violinist Robert McDuffie was to be the featured violinist with pianist Christopher Taylor in a special event in Harris Hall (which meant season pass holders had to buy it separately). He was also scheduled to play the quintet the following evening in the Benedict Music Tent concert featuring pianists Misha and Cipa Dichter. But McDuffie injured his side jogging, making it painful to pick up a violin, so the festival had to scramble to fill the void.

There are plenty of worthy artists around. Beth Newdome, formerly associate concertmaster of the Atlanta Symphony, played Schumann's Violin Sonata No. 1 in A minor. Schumann's Three Romances for oboe and piano replaced the scheduled Violin Sonata No. 2, the oboe part taken by Jeannette Bittar, who has played with Yo Yo Ma's Silk Road Ensemble. Maybe McDuffie would have made more of the two sonatas. Both performances were earnest, and Taylor showed himself to be an alert collaborator.

With juicier material -- i.e., the Piano Quartet in E-flat major -- Taylor joined forces for a remarkably vivid performance with ‘cellist David Geber, a founding member of the American String Quartet, violist Lawrence Dutton of the Emerson Quartet and pinch-violinist Alexander Kerr, concertmaster of the Concertgebouw. From the slow introduction, which seemed to suspend itself in mid-air until it erupted into the first theme, this was exciting music making. Each instrument seemed to be singing, appropriately enough, in the lovely Andante cantabile, and the finale ripped to a brilliant conclusion.

The long first half (almost 90 minutes) of the Dichters' concert seemed singularly ill suited to the vast open spaces of the 2,050-seat tent. Bilder aus Osten: Six Impromptus, for one piano four hands, and Six Etudes in Canon Form, for two pianos, came off as innocuous drawing room music. They had their lovely moments, but I'll bet they were more interesting to play than to hear. Andante and Variations, for two pianos, two ‘cellos and horn, was more appropriate for the surroundings. Margo Tatgenhorst Drakos, current ‘cellist for the American String Quartet, and David Wakefield, horn player for the American Brass Quintet, injected some much-needed life into the proceedings.

There was audience confusion over when to break for intermission, as about half of the crowd got up and left after the Variations. An announcement had to be made to bring them back for Misha Dichter's rushed, perfunctory solo performance of Viennese Carnival. The ensuing intermission was mercifully short, lasting just over 10 minutes.

Joining Misha Dichter for the Piano Quintet in E flat major, Drakos and Dutton returned along with violinist Elizabeth-Lim Dutton, the violist's wife. Peter Winograd, first violin of the American String Quartet, stood in for McDuffie in the lead. The broad, heroic open theme brought me bolt upright in my seat. In the lyrical sections that followed, Drakos and Dutton traded off phrases seamlessly. Winograd's intonation was spot-on.

Dichter, however, seemed have a different sense of the rhythmic pulse than the four string players did, so the livelier moments lacked the juice they can attain in full rev. It took a couple of iterations of the recurring phrase in the fast scherzo to the notes as groups of three, and Dichter's playing just seemed uninflected. He kept up the pace, however, and the result was several steps up from the first half.

The Schumann half of Friday's Aspen Chamber Symphony concert went off splendidly as music director David Zinman led a buoyant performance of the composer's Symphony No. 1 "Spring". But pianist Yefim Bronfman completely overshadowed it with protean Beethoven and an incendiary Prokofiev encore.

Before a packed tent, Bronfman, a festival favorite, took a pure, unaffected approach to Beethoven's Piano Concerto No. 3. There is nothing willful or studied about what he does. It just flows out, expressive, instinctive. He has enormous technique at his disposal, but what came out was never showy.

Not with Beethoven, anyway. For an encore, Bronfman, born in Tashkent, went back to his Russian (well, Soviet) roots and tore into Prokofiev's Toccata in D minor, Op. 11, with almost alarming savagery. It couldn't have been more of a contrast with the Beethoven, and the crowd leapt to its feet with a second -- and richly deserved -- standing ovation.

Mendelssohn's Overture to the Fairy Tale of the Fair Melusine got the concert started on a pleasant note. Much less familiar than the composer's other overtures -- Fingal's Cave and Midsummer Night's Dream come to mind -- it has a sort of reserve that set up the more overt music of the concerto beautifully. After intermission, Zinman drew lively, open-textured, fresh-faced playing from the orchestra, just the thing for this easy-going, tuneful romp. It brought to a close one of the more fully satisfying concerts of the year.

Those who came back for the American String Quartet's evening concert were rewarded by clear-headed, precise readings of Schumann, Shostakovich and Brahms. J.D. Landis, whose novel, Longing, is about Robert and Clara Schumann, added welcome texture to several programs during the week, including this one, commenting on the relationships among the Schumanns and Brahms. Reading from their letters and other historical materials, he suggested that Clara's relationship with Brahms was more than mere friendship.

The ASQ's program began with the Schumann Quartet No. 3 "Clara" and ended with the Brahms Quintet, in which they were joined by violist John Graham, professor at Eastman School of Music. Neither performance left anything to complain about, but Shostakovich's magnificent String Quartet No. 3 simply overwhelmed them. The ASQ's immaculate performance emphasized the lyrical moments and sighing moments of repose more than the gritty, hard-edged soul of the piece.