Not one but 2 special occasions will be celebrated when the Ann Arbor Symphony Orchestra offers its 14th annual Mozart Birthday Bash on Saturday night at Hill Auditorium.

Not only will Mr. Mozart get his due (he’d have been 254 years old on January 27), but A2SO maestro Arie Lipsky will be marking his 10th year at the helm of the ensemble.

“The whole season is very special for me,” Lipsky acknowledged.

“The symphony has really grown (over the last 10 years),” he said. “I think particularly they are playing better, more cohesively, and we have had wonderful new players to add to the superior core. We have more subscribers than ever, even in these economic times (and) that’s a vote of confidence. I am very pleased.”

All that, of course, leads into the topic at hand, Saturday’s all-Mozart program, which consists of Divertimento K. 136, the Horn Concerto No. 3 in E-flat Major with A2SO horn principal Andrew Pelletier as featured soloist, and Mozart’s famous Requiem Mass in D minor. The Requiem will be performed with a choir of over 200 voices from Pioneer, Huron and South Lyon high schools, augmented by singers from Measure for Measure, the Choral Union, the Vocal Arts Ensemble and Temple Beth Emeth, plus soprano Jennifer Larson, mezzo-soprano Sarah Nisbett, tenor John Charles Pierce and bass Stephen West as featured soloists.

“This is a real made-in-Ann Arbor concert — I just love it,” Lipsky said. “All the soloists and choruses have direct ties to Ann Arbor. It’s just a nice celebration of Mozart.”

Some of the soloists will be familiar to those who saw the symphony’s “Magic Flute” last winter: Larson, Nibsett and West all filled key roles.

Lipsky admits it’s a challenge to offer the Requiem because of the huge number of performers involved.

“The chorus is not a regular chorus that sings with the symphony,” Lipsky explained. “I will actually individually go to each of the schools and work with the choruses, then put everybody together during the week for one rehearsal. Then I will have a separate rehearsal with the soloists. Friday night we will have all the forces fully together. It’s difficult, but the music is just angelic, even godlike.”

The mass was commissioned anonymously in 1791 by Count Franz von Walsegg, who wanted to pass the piece off as his own to commemorate the death of his wife. Mozart was in declining health, and died before completing the Requiem. Franz Xaver Süssmayr finished orchestrating it from what Mozart left, producing the version with which audiences are familiar today.

“We usually think of Mozart of a light composer, but his Requiem is one of the greatest masterpieces,” Lipsky said. “It is a very, very powerful and religious piece. It’s his last piece … there’s the very famous “Lacrimosa,” where the music just goes up and up and then at one point it just goes down and these are the last notes that Mozart composed. It’s so dramatic. It is scary in a way.”

The program the precedes the Requiem is compelling as well, Lipsky said. The evening starts with a divertimento, a light-hearted piece written by a young Mozart at maybe 18 or 19 years old, followed by the Horn Concerto No. 3.

Watch a preview of A2SO's Mozart Birthday Bash:

Mozart wrote all 4 of his horn concertos for friend Joseph Leutgeb, and enjoyed making them as tricky as he could. The work on Saturday only lasts about 15 minutes, and uses clarinet and bassoon with strings as its instrumentation to create a warm, rich core to support the horn.

“All the horn concertos Mozart wrote are very, very difficult, but we have a wonderful player,” Lipsky observed. Pelletier, who has played with the A2SO since the fall of 2006, is currently Assistant Professor of Horn at Bowling Green State University and sits in the Sherman and Sylvia Funk Principal Horn Chair.

Saturday night’s affair is not the only Mozart the A2SO has planned for this weekend. As part of the Symphony’s Family Concert Series, the group presents the “Mozart World Tour: Ann Arbor” on Sunday afternoon at the Michigan Theater. During this A2SO-commissioned one-hour play, written by Ann Arborite Jeff Duncan, actors tell a story while the ensemble plays some of Mozart’s greatest pieces.

“It’s based on an imaginary trip Mozart took to Ann Arbor,” Lipsky said. “Three actors are in the play — Mozart, his sister, and his father — it’s a fun way to enjoy the afternoon and Mozart.”

Roger LeLievre is a freelance writer who covers music for AnnArbor.com.

PREVIEW 14th Annual Mozart Birthday Bash Who: Arie Lipsky conducts the Ann Arbor Symphony Orchestra, plus guest soloists and a choir of over 200 voices at this annual concert celebrating Mozart’s birth. What: The program consists of Divertimento K. 136, Horn Concerto No. 3 in E-flat Major and Requiem Mass in D minor. Where: Hill Auditorium, 825 North University Avenue. When: 8 p.m. Saturday, January 23. How much: $6-$49. Additional events: A pre-concert lecture covering the evening’s repertoire will take place from 7-7:30 p.m. on Saturday at Hill Auditorium. Lecturers will include Arie Lipsky, vocal soloists, and A2SO principal horn and soloist Andrew Pelletier. On Sunday at 4 p.m., the A2SO presents the family friendly one-hour show “Mozart World Tour: Ann Arbor” at the Michigan Theater (tickets are $6-$15). Details: A2SO web site or 734-994-4801.