In a large bowl, cream butter and sugar. Beat until mixture is light and fluffy. Add eggs 1 at a time, beating well after each addition. Beat in sour cream, brandy, vanilla, and rum. In another bowl, sift together the flour, salt, and baking soda. Stir the flour mixture into the butter and egg mixture. Pour batter into buttered Bundt pan and bake for 1 hour at 325°, or until cake tester inserted in the center comes out clean.
Cool the cake in the pan on a rack for 1 hour. Then, turn it out of the pan on a rack to cool completely.