Preheat oven to 350. Grease and flour 2 loaf pans. In a large bowl, with an electric mixer, blend flour, sugar, salt and baking powder on low until all ingredients are well mixed. Add butter, sour cream, and 3 eggs. Mix on medium until dry ingredients are moistened and beat on high 2 minutes then scrape bowl. Add remaining 3 eggs, one at a time, alternating with amaretto. Beat well after each addition. Blend in poppy seeds on low speed. Pour batter into prepared pan and bake 50-60 minutes or until toothpick inserted in center comes out clean. Cool in pan 10 minutes and invert cake onto a rack to cool. When cake has cooled completely, lightly dust top with confectioners' sugar.