When Minnesota Orchestra principal trombone R. Douglas Wright blew the final note of James Stephenson's "Pillars" at Orchestra Hall Thursday morning, he puffed with visible relief, and possibly exhaustion.

No wonder: Stephenson's new concerto gives its four soloists — two trombonists, a bass trombonist and a tuba player — a super-strenuous workout over three movements lasting 25 minutes.

Writing for such an unusual combination of instruments can lead to token flashiness and superficiality. "Pillars" had a strong musical narrative, however, from the Brucknerian gravity of the solo chorales in the opening movement to the rumbling finale, stampeding like a herd of buffalo across an open prairie.

The passacaglia middle movement was the emotional heart of Stephenson's concerto. Wright's doleful trombone solo gradually developed into a full-throated lament, flaked with references to the funeral jazz of New Orleans, with tolling bells in the background.

The finale was perhaps a trifle overextended, and the strings occasionally seemed swamped by the excellent quartet of Minnesota Orchestra soloists. But "Pillars" made a bold impression, commandingly conducted by Osmo Vänskä.

Mahler's Fourth Symphony was the program's other work, marking the halfway point in the complete cycle of Mahler symphonies Vänskä is undertaking with the orchestra. So far the hallmark of this performance/recording series has been the startling clarity of texture Vänskä achieves in highly detailed, complex music, with a choice of tempos that give expressive elbowroom to the players without allowing emotional self-indulgence or bathos.

These qualities again suffused Vänskä's bristlingly vivid interpretation of the Fourth Symphony. The opening movement's development section tingled with the ceaseless activity of the natural world, especially in a splendidly squawking woodwind section.

The flickering, mock-macabre scherzo was perfectly unraveled, the playing as sharply etched and fine-honed as a Dürer woodcut. Disarmingly tender playing from the cellos opened the blissed-out slow movement, which thrummed with ecstasy in its final, crushing crescendo.

The symphony's finale is a song depicting a child's idyllic experiences of heaven, often performed in ways that seem either too knowingly adult or exaggeratedly infantile.

The soprano Carolyn Sampson walked that particular interpretive tightrope with insouciance. Stationed in an unorthodox position on a rear-stage riser beside the trumpets, she looked and sounded ethereal, deploying her operatic experience for a range of facial expressions communicating the delight and wonder of Mahler's child protagonist.

Vänskä's accompaniment was both affectionately supportive and bitingly incisive, and he navigated the symphony smoothly to its soft, becalmed conclusion, the double basses tapering to peaceful restfulness.

The Swedish record company BIS will record this pin-sharp, beautifully articulated version of Mahler's Fourth at Orchestra Hall next week. The company's Beethoven and Sibelius recordings with Vänskä and the Minnesota Orchestra already enjoy reference status. This new Mahler series is proving just as exceptional, and could ultimately turn out to be even better.

Terry Blain is a freelance classical music critic for the Star Tribune. Reach him at artsblain@gmail.com.