Sunday was Mozart’s birthday. It was also Édouard Lalo’s and Jerome Kern’s, as you might find in any “on this day in classical music” source. Neglected just about everywhere, though, was the fact that on Sunday the Armenian composer Tigran Mansurian turned 80.

Even so, Mansurian does have an international following for his spiritually riveting, exquisitely fabricated scores that link him stylistically with prominent Eastern European contemporaries such as Estonia’s Arvo Pärt, Poland’s late Henryk Górecki, Ukraine’s Valentin Silvestrov and Russia’s Sofia Gubaidulina and the late Alfred Schnittke. Mansurian, moreover, is championed by a number of prominent musicians, including violist Kim Kashkashian, pianist Alexei Lubimov and violinists Leonidas Kavakos and Patricia Kopatchinskaja, all of whom have made sterling recordings of his music mostly for ECM. Once you hear something by Mansurian you are not likely to forget it.

Dilijan, which features works by contemporary Armenian composers along with typically world-class performances of standard repertory chamber works, has been Mansurian Central from the start. Fifteen years ago, violinist Movses Pogossian and Mansurian mapped out the series at a Starbucks in Glendale, where the composer used to quietly spend part of the year composing far from the Yerevan limelight.

Quietly, indeed. Over the years Dilijan has been the main conduit for Mansurian’s music in the U.S., and it featured stellar performances, but it never attracted much attention outside of the large local Armenian community. Sunday’s full house was no exception, attracting little outside attention despite offering commanding performances from musicians like Kashkashian, Pogossian and Los Angeles Philharmonic principal clarinetist Boris Allakhverdyan.

The program covered a fairly narrow, if exceptionally deep, swatch of Mansurian’s output, with works written between 1993 and 2006. They were all of intense poetic content, rapt in their relationship to the soul of Armenia and its music, dealing with matters of love, life and, especially, death. We feel, we suffer and then we die, these works seemed to suggest, so how do we make our short existence matter?

It would, nonetheless, be a mistake to get too wrapped up in the monastic side of Mansurian. For all of his spiritual intensity, he achieved his mature voice the hard way, and he has always been of many sides.

That late voice, the one Mansurian is known for, strives for a purity of sound and _expression_ based on elements of traditional Armenian melody and the country’s traditional and liturgical music, its language and poetry, to say nothing of its landscape. But under it all is a highly cosmopolitan composer.

Early on Mansurian participated in the post-World War II European avant-garde. He wrote film music including the soundtrack for the dazzling 1969 Soviet art film classic “The Color of Pomegranates” and, of all things, a much later L.A. police thriller, “Camera Obscura.”

The earliest piece on Sunday’s program was Mansurian’s agitated String Quartet No. 3, a musical letter written in 1993 during Armenia’s struggle for independence. Rather than escaping into spiritual grace, Mansurian pulls Armenian melody apart with dark, mournful dissonant counterpoint, a startlingly vivid description of what was happening to his country.

The biggest piece was “Ars Poetica,” an hour-long a cappella choral setting of 10 poems by Armenian poet Yeghishe Charents. There are songs of sleepless night and its terrors; enchanting odes to the feminine, be that Mother Mary or Manon Lescaut; doleful songs of autumn, dramatizing the inevitable; and a long epilogue in which the poet imagines how he will be remembered, if he is remembered at all.

Mansurian makes these sentiments stick, gripping us in our fears and desires, and the Lark Master Singers, led with arresting physical immediacy by Vatsche Barsoumian, added an extra shot of raw vitality. This is an amateur volunteer chorus able to enter fully inside the score with an immediacy that makes a professionally polished ECM recording feel a little tame in comparison.

“Ars Poetica” was finished in 2000, and the “Three Medieval Taghs” for viola and percussion and the clarinet quartet “Agnus Dei” followed over the next six years. This is the kind of music for which Mansurian is best known. Through melody of condensed _expression_, every tiny gesture resonates as it lingers with a sense of timelessness in the air.

Mansurian gives the impression here of not so much overcoming anguish (let alone transcending it) as accepting and absorbing the pain of loss. He evokes spiritual pain to remind us what it means to be alive, to feel closer to our bodies and being.

When Allakhverdyan’s clarinet floated, barely heard, in “Agnus Dei,” it became the listener’s job to try to hang on to the life of sound waves. When Kashkashian’s viola and the metallic percussion seemed to cry for all the sorrow in “Tagh for the Funeral of Our Lord,” there was a sense that this elegy is supposed to go on forever, lest we ever forget to value each breath.