Members of the Bangor Symphony Orchestra have grown used to standing ovations. They get two or three of those a season from their loyal subscribers. The demand for an encore, however, is pretty rare in classical music circles.

The symphony’s collaboration with the Kruger Brothers, a bluegrass band based in the mountains of North Carolina with Swiss roots, earned the orchestra a well-deserved encore for the two-hour program, “Music from the Spring: A Romantic Serenade for Banjo, Guitar, Bass & Orchestra,” on Saturday night.

Although the trio, made up of brothers Uwe and Jens Kruger and Joel Landsberg, have been playing the material for the past 20 years, the concert was the first time Jens Kruger’s compositions have been orchestrated. Last week, bass player Landsberg described the program to the Bangor Daily News as “the Kruger Brothers with a very big backup band.”

The strength and the power of the symphony’s string section at times seemed to overpower the trio, who were joined by guest percussionist Josh Day. Although the problem was remedied by an adjustment of the group’s microphones during intermission, the BSO drowned out Jens Kruger’s delicate banjo picking and his brother Uwe Kruger’s fine guitar strumming during the first quarter of the show.

The concert began with the most traditional bluegrass compositions. Instead of adding depth to them or lifting them up, it sounded like the orchestra was trampling all over them or mocking the contemplative tone that the best of bluegrass offers.

Once the trio picked up the pace, however, the orchestra fortified the players and joined them in a fevered and frenzied journey to intermission in “Run, Run, Run” and “Wilkes County Breakdown.” These pieces benefited greatly from having more than 100 players join the fray of what even casual bluegrass fans recognized as the familiar fast-paced style of instrumental songs most familiar to Americans from movies and television shows set in the Appalachian Mountains.

During the second half of the concert, once the microphone problems were solved, the orchestra and the band blended their sounds best in Jens Kruger’s jazzy compositions. This turned out to be the musical high point of the evening. The banjo player’s skill and versatility was evident as he played the intricate piece and brought unexpected intensity from his instrument. The orchestra added breadth and depth to the song that gave new meaning to the interpretation of bluegrass.

The audience, a combination of Kruger Brothers and BSO fans, truly enjoyed the concert. Its enthusiasm nearly was eclipsed by that of conductor Xiao Lu-Li. He did not just bounce as he led the orchestra he often hopped in time to the music.

Only in Bangor, he said as the concert-goers rose to their feet for the last time, could a bluegrass band, with two members born in Switzerland, play with the nation’s oldest community orchestra as it was led by a Chinese conductor.

“We could have peace in the world,” he said, “if the world has more Kruger Brothers.”

Only time will tell if Li is right, but the trio’s collaboration with the BSO was definitely the start of a beautiful friendship.