Most of us feel fairly chipper if we make it past the age of 50 without replacement parts.Imagine the condition of Sergei Rachmaninoff'sAll-Night Vigil(Vespers), a 100-year-old war horse of Russia's golden age of sacred music with 1,000-year-old parts. Performed by over 90 voices and led by Bay Area Russian choral ensemble Slavyanka and Artistic Director Irina Shachneva, there's a three-night, three-location party to celebrate the composition's 100th anniversary. Casting a reverential mood, the multisectioned choral work begins without voices. Instead, Shachneva has authentic Russian church bells chase away demons before Georgi Sviridov's original composition, set to a Pushkin poem, suggests the onset of twilight. Rachmaninoff kicks in when three Orthodox services show off ancient chants, six-, seven-, eight- and even one 11-part harmony reveal Slavyanka's command, and a hymn of blessing sends the audience floating home on a cloud of choral bliss. A sign on the door should read, "Enter aged, exit ageless."