Now and then this world of ours produces a jazz singer with a voice that can melt the coolest soul. Such a person is Sophie Milman, a young jazz singer based in Canada. She is the point at which the lines of three rich traditions meet: Russian spirit, Jewish intensity, and black American swing. If the goal of your evening is romance, there is no better place to go than this little jazz show. (Dimitriou's Jazz Alley, 2033 Sixth Ave, 441-9729. 7:30 pm, $21.50, all ages. Also Wed April 9.)