MOSCOW — It's 1 A.M. in the frozen downtown. Roman Sorkin puts a CD by Syrian-Egyptian musician Farid al-Atrash on his stereo. He stretches out on the sofa in the living room of his apartment — in a wealthy part of town in a building filled with actors who were well-known during the Soviet era — and sips a glass of wine. His cousin Yan Sorkin, a self-employed architect...