The Boston musical season may be over soon, but so much is happening, it seems less like a winding down than a revving up. We’ve had world premieres by two major composers, a production of a rarely performed Mozart opera, a rarely performed Stravinsky masterpiece, a rich recital by one of Boston’s most important pianists, and a return visit by a well-liked but long-absent conductor. Not all of this was completely satisfying, but my head is still spinning from the abundance.

Take the BSO, for instance. The last two programs consisted entirely of music by Russian composers, from Tchaikovsky’s familiar Pathétique Symphony to the world premiere of Sofia Gubaidulina’s new orchestral work, The Light at the End (at the same concert with a work long-associated with the BSO, Prokofiev’s Classical Symphony, " marking the 50th anniversary of the composer’s death " ).

The week before, we got much rarer Prokofiev, his 1921 comic ballet Chout ( " The Tale of a Buffoon Who Outsmarted Seven Other Buffoons " ), which the BSO has never performed complete (it’s 50 minutes long), though selections from it have been heard here several times between 1926 and 1962 (in 1938, Prokofiev himself conducted excerpts). It got an exhilarating, raucous presentation under the slyly restrained direction of Russian conductor Gennady Rozhdestvensky, who convinced you that every note was a nasty, nose-thumbing parody of something, even if you didn’t know exactly what. Still, I’m not sure completeness was the greater virtue here.

This made a vivid contrast with the preceding piece on the program, Stravinsky’s exquisite " melodrama " Perséphone, its floridly literary yet still moving text by André Gide about the need for cycles of death and rebirth luminously recited by actress Marthe Keller (Funeral in Berlin, Marathon Man, The Formula). Stravinsky conducted the American premiere with the BSO in 1935 (the BSO played it only once again, in 1976). Rozhdestvensky took his time, preserving the delicate textures and piquant harmonies without losing the rhythmic bite, the forward motion. Tenor Vinson Cole sang the narrator’s role stylishly, and the Tanglewood Festival Chorus and American Boychoir were marvels of subtlety and eloquence.

The BSO has an odd problem with its wind section. The second-desk players — Fenwick Smith (flute) and Thomas Martin (clarinet) seem more imaginative and characterful than the current principals, excellent as they are. Associate principal bassoon (Richard Ranti) is also excellent. But principal oboist John Ferillo is a far more sophisticated player than assistant principal oboist Keisuke Wakao. Unfortunately, Ferillo rarely gets to play with Smith, Martin, and Ranti. But in these last two concerts, the casting was just right: Wakao in the brash Chout, Ferillo in the refined Perséphone, and in the Classical Symphony and Gubaidulina premiere, the perfect teaming of Ferillo with Smith, Martin, and Ranti.

Conductor Kurt Masur hasn’t led a full program with the BSO at Symphony Hall in 15 years. He got the Classical, which he’s done here before, off to a bubbly start, but the slow movement turned limp and syrupy. The Pathétique was a mixture of sloppy ensemble and disjointed phrasing — more effortful and manipulated than felt. There were luscious cellos in the otherwise bland waltz. The third movement march was so fast it seemed unmarchable (it garnered the usual smattering of misplaced applause). The sad Adagio lamentoso finale was more focused, but I’d already lost interest.

It was wonderful that the BSO commissioned a piece from Gubaidulina, who is surely the greatest living Russian composer (though she’s been living near Hamburg), wonderful to hear it for the first time, and wonderful that she was present. But The Light at the End didn’t strike me as one of her very best pieces. It was gorgeously orchestrated, of course, with fascinating combinations of percussion: she says the title, which was only recently announced, " derives from the bright sound of the antique cymbals that bring the coda of this piece to a close. "

Since this is Gubaidulina, it surely also refers to the spiritual transcendence that may follow the storms of life. The guiding principal is technical: the conflict between instruments (especially brasses) that have a " natural " harmonic scale and instruments that use the adjusted, or " tempered, " scale that has become standard practice on keyboards (as in Bach’s Das Wohltemperierte Klavier). There’s an edgily " dissonant " duet for horn (James Sommerville) and cello (Jules Eskin).

The piece starts with a mysterious alto flute, chimes, and whirring strings, followed by the Timex ticking of a flute and harp and horns wailing like a siren. The orchestra stirs up tremendous whirlwinds studded with thunderclaps; then come passages like shimmering raindrops. A tuba growls in the basement, like a dying animal. Suddenly, the portals of Heaven swing open: chimes! high string glissandos! harps! And finally this all dissolves into radiant silence. Masur led with authority, and the playing, for a premiere, was estimable.

No composer has written music that conveys a more profound sense of spiritual suffering than Gubaidulina; but like its title, The Light at the End has an element of sentimentality about it, of corn — a quality I don’t associate with Gubaidulina. Maybe repeated hearings (or a different performance) will provide a more reliable perspective.

THE OTHER PREMIERE was John Harbison’s Second Piano Sonata, which was played by its dedicatee, Robert Levin, in a Boston Marquee event sponsored by the FleetBoston Celebrity Series at Jordan Hall. Levin is a familiar concerto performer, maybe best known for his explorations of the historical practice of improvisation. I’d never heard him in a full recital.

His program was astonishingly ambitious. It started with Beethoven’s large-scale early Opus 7 Sonata in E-flat. But the real center was Bach’s A-minor Fantasia and Fugue. Levin jumped from Beethoven to Bach by way of an improvised modulation from E-flat to A minor, a familiar tradition, he told us, in the first four decades of the 20th century. From the Bach, he launched — breathtakingly, and without pause — into the violent contrapuntal complexities of Hindemith’s three-movement Klaviermusik, Part I.

My reservation about Levin’s brilliance concerns his apparent indifference to color. No pianistic perfume here. He can suggest a piano-playing threshing machine, a sound that can become as tiring as it is riveting. I’ve often felt that he was shaping the music from the outside.

But not this time. The highly inflected Beethoven was gripping throughout. The slow movement sounded like an intimate conversation that boiled over into an argument. The connecting improvisation was compelling, and the multiple strands of the Bach fugue had an impressive and beautiful clarity. Levin mentioned that the Hindemith was completed in a train station, an apparent irrelevancy until you heard its prestissimo choo-chooing. It kept my own motor running all the way through intermission.

Harbison’s new piano sonata, completed in May 2001, also is large-scaled and ambitious and also looks back to Bach, with the ground bass in the third-movement Ricercar (both " Tranquillo " and " Brusco " ). The alternately majestic and delicate Intrada (with its undercurrent of buried blues, a syncopated heartbeat that throbs throughout the entire piece) leads into the sonata’s emotional center, an Aria (marked " Lambente " ) that starts out rhetorical and passionate before bursting into song. Several glistening passages fluttering in the upper reaches of the keyboard return at the end of the movement. I found the series of seven final variations surprising, touching, and ambiguous. I’m not quite sure how they fit, and I can’t wait to try again.

But the concert wasn’t over yet. Levin closed with César Franck’s demanding Bach-inspired Prelude, Chorale, and Fugue (not played as often as it used to be). His fingers seemed to be tiring, but not enough to inhibit a triumphant conception, and they had enough energy left for three encores: one of Mendelssohn’s Lieder ohne Worte; a piece whirring over a chordal melody in the bass that even musicians in the audience couldn’t identify (it turned out to be Alkan); and Yehudi Wyner’s Sauce 180, a delicious bagatelle named after a Brandeis music course.

THREE YEARS AGO, the BU Opera Institute ventured into a student performance of the most formal — and most dated — of all operatic styles, " opera seria " ( " serious opera " ), with a remarkable production of Mozart’s last opera, La clemenza di Tito. This year, stage director Sharon Daniels and conductor William Lumpkin had less success with Mozart’s earliest great opera, Idomeneo, also an opera seria. By the time he composed Tito (after Figaro, Don Giovanni, and Cosí fan tutte), Mozart had figured out how to inject opera seria with drama. Composed a decade earlier, Idomeneo has some of Mozart’s most sublime vocal music, but it’s extremely static. " Fuggiamo, fuggiamo! " ( " Let us flee! " ), the chorus repeats, terrorized by a sea monster. The BU chorus was superb, but how do you flee while you’re still singing?

Daniels isn’t the first director to be defeated by opera seria. Her imaginative and pointed touches were outweighed by her inability to find a convincing way for characters to move and interact. Whether they sang standing, sitting, or lying down seemed arbitrary. Clichés of 18th-century formality mixed uncomfortably with clichés of contemporary realism (chorus members miming conversation while someone is singing is particularly inappropriate here). In Lisa Geiger’s largely unflattering costumes (including a leopardskin wrap for the seething villainess), the singers ambled like American college students, not Minoan royalty striding across a throne room. A seaport with hanging fishnets and a chillingly stark Temple of Neptune worked best among Richard Chambers’s mélange of abstract and realistic sets.

Lumpkin seemed to be conducting to keep the orchestra together rather than for incisive phrasing or melodies that breathed. The pace plodded. The strings had serious intonation problems.

In Tito, a very difficult role was taken by the extraordinary young mezzo Sandra Piques Eddy, who now sings at the Met and New York City Opera. Idomeneo had two casts, but no one in the cast I heard sang or acted on her level. A couple of singers, tenor Alan Schneider in the title role (Pavarotti’s best Mozart part), and soprano Sarah Davis as the Trojan princess Ilia, did demonstrate both stage presence and voices of considerable potential. They’ll probably never have to sing anything harder in their lives.