Exactly how much rediscovery a hugely popular musical figure such as Serge Rachmaninoff needs might seem questionable when you first hear of the Pittsburgh Symphony Orchestra's choice for a month-long festival. After all, he is the composer of some of the industry's most beloved works, like the C-Sharp Minor Prelude and the Third Piano Concerto, and his legacy is as one of the most prodigious pianists of all. (He played with the PSO on several occasions).

But the truth is, all classical composers are in need of contextualizing. Not only does the sheer amount of pieces force a quick romp through them, but we tend to rely on oft-repeated vignettes in which stereotypes generally rule.

That's why last night's opening concert of the "Rediscovering Rachmaninoff" festival is the sort of thematic approach to music the PSO and other orchestras should offer often to add understanding to central figures. An in-depth treatment also allows obscure works and new artists to come to the table. Last night at Heinz Hall, both proved to be highlights.

Rachmaninoff's final work, "Rhapsody on a Theme of Paganini," introduced Macedonian pianist Simon Trpceski. "I am pure Russian school, but with flexible opinions about music," he told me in an interview, and that came true in a wonderfully imaginative playing.

While still offering the needed resonating tone and crisp technique, Trpceski opened his imagination, unleashing colors and exuberant phrasing that belied the predominant dour-looking image of Rachmaninoff. (See? Stereotypes falling already.) The result was organic in nature. Nothing felt tacked on -- not certainly the famous Eighteenth Variation, which unfolded modestly and without the typical spotlight many pianists give it. He played Chopin's Waltz No. 19 in A minor as an encore. Clearly a pianist we need to hear again.

Conductor Gianandrea Noseda cultivated Trpceski's vigor and let the work bound forth, bringing out several vibrant solos from the orchestra. Noseda, who poked fun at his ultra-fast tempos in Schubert's Ninth Symphony last week, continues to charm the audience. Noseda hit the musical mark with Rachmaninoff's fateful Symphony No. 1, which flopped in its premiere in 1897.

The conductor treated the aggressive four-note motive of the symphony like an idee fixe, fitting for the compulsive composer. In nearly every statement, it sang out stridently. But the conductor's grasp of structure made the reading. He let the orchestra float in sections, such as clarinetist Michael Rusinek's exquisite opening theme or the string playing in the second movement, but had it dig in with edgy, unsettling attacks whenever the darkness of the work rears its apocalyptic head. It was a reading that didn't pander to the work's effects but sought to let the themes tell the story. Without question a work that needs to be heard more.

In between, the Mendelssohn Choir of Pittsburgh and baritone Vasily Ladyuk offered another lesser known work, Rachmaninoff's "Spring Cantata." Ladyuk didn't always project enough in the harrowing tale of a husband's near murder of his unfaithful wife, but his rich, dark timbre fit the cantata well and the choir, Russian diction aside, was an able companion.

The program repeats at 8 tonight and 2:30 p.m. tomorrow.