A lot of classical concerts fall prey to the masterpiece syndrome: Line up two or three great pieces, play them one after the other, and you’ve got an easy — some might suggest foolproof — hit parade.

Yet this season, the Cobb Symphony Orchestra is asking its audience to consider the broader implications of everything it hears, with the hope that a few provocative ideas are thrown into the mix. CSO music director Michael Alexander described the thematic programming as simplicity itself: “We take diverse things and put them together.” If it works as hoped, these will lead to unexpected consequences.

Perhaps the strangest bedfellows will be heard March 5 at the First United Methodist Church of Marietta for a work called “The World Beloved: A Bluegrass Mass.” The composer is Carol Barnett, with a small but serious reputation in the choral community, especially in Minnesota, where she’s a small-college professor.

It’s a hybrid Mass, sung in English, which premiered in 2006 and is scored for chorus and a kind of five-piece hillbilly philharmonic consisting of fiddle, guitar, upright bass, mandolin and banjo. After the premiere, some of the performers commented that the classically straightlaced choir was pushed into a folk idiom while the veteran bluegrass band Monroe Crossing was asked to sit up straight and play the correct notes on the charts.

The theology might raise conservative eyebrows. Marisha Chamberlain’s libretto, incorporating elements of the Latin Mass with Appalachian tunes and ballads, has an inventive “Gloria” section praising God “for feather, fur, for scale and fin.” The work begins with a male God and, across the Mass’ 45 minutes, ends with, “They say God loved the world so dear, She set aside Her crown.”

Yet by all accounts, the cultural and musical mash-up was a sterling success.

Bryan Black, the Cobb Symphony’s choral director, had heard of “The World Beloved” and its budding popularity. He brought it to music director Alexander’s attention when the season was being planned. “Our chorus is loving it,” Alexander said.

Although the Mass is getting some play around the country, most groups hire just a pianist to accompany the choir. “We’ve got a proper bluegrass band,” the conductor said, “but that’s been the trickiest part, to find top-notch bluegrass musicians who can also read music!” (For the premiere, the members of Monroe Crossing, who don’t read music, learned the part by rote from MIDI computer sound files.)

Thus a CSO section violinist, Heather Hart, will take the fiddle role and CSO principal bassist Bob Goin will thump the bass line. The virtuosic banjo part, the glue that binds the Mass together, has been the trickiest part to cast, and the slot still had not been filled.

The full 70-member CSO will perform a more traditional pairing — major symphonies by two Russian titans — one week later, March 12-13, at Kennesaw State University’s acoustically splendid Bailey Center.

Yet the two works on the program still meet the diversity criteria for the season: Dmitri Shostakovich’s brash and electrified Symphony No. 1 and Sergei Rachmaninoff’s lush, panoramic Symphony No. 2.

“The Shostakovich is the hardest thing we’ll play all year, flat out,” Alexander said. “As the textures get thinner, you can hear the individual strengths within our orchestra. It will help us grow.”

Shostakovich’s First Symphony, his graduation exam from the Leningrad Conservatory in 1925, is jittery, sharp-edged, urban, “new” and impetuous — in a way that reveals a 19-year-old genius at the start of a towering career. It contains none of the emotional anxiety and encrypted layers of meaning that scar the composer’s style after his encounters with Soviet dictator Stalin, who controlled the arts with the same iron grip he used in politics and the military.

Compared to the jazz-age freshness of Shostakovich, Rachmaninoff sounds like the dying last vestige of the old 19th-century aesthetic. But what a 1907 sound: those endless melodies that are among the most gorgeous in the repertoire, those expansive vistas that are breathtaking, the Adagio so hummable it could be a hit on the pop charts.

Pairing these Shostakovich and Rachmaninoff symphonies, Alexander said, “is a look into how music split apart in the early 20th century, going into modernism versus trying to hang onto what was really beautiful just a little while longer.”

Pierre Ruhe is classical music critic of www.ArtsCriticATL.com