It’s more than a little ironic that Rebecca Sullivan discovered her jazz calling in Russia. Remember, not so long ago, when jazz and other American music were banned there? But the Cold War was long over in 2004, when she spent a semester abroad studying Russian literature in St. Petersburg. Jazz clubs abounded there. And she could get into them, free of the drinking-age restriction that kept her out of nightclubs in her college town of Portland, Oregon. Hearing the music performed live was a revelation. “I had no idea songs could sound like that,” she said.