Prepare Pecan Streussel: Combine first 4 ingredients in a bowl until mixture resembles small peas. Stir in 3/4 cup pecans. Set aside.
Prepare Pound Cake Batter: Preheat oven to 350 degrees. Bake 1 cup finely chopped pecans in a single layer pan 5 to 7 minutes until lightly toasted and fragrant. Cool 20 minutes. Reduce oven temp to 325 degrees.
Beat butter at medium speed with heavy-duty stand mixer until creamy. Gradually add granulated sugar, beating until light and fluffy. Add eggs, 1 at a time, beating until just blended after each addition.
Stir together flour and baking soda; add to butter mixture alternately with sour cream, beginning and ending with flour mixture. Beat at low speed until just blended after each addition. Stir in vanilla.
Pour half of batter into a greased and floured 10-inch (12-cup) tube pan. Stir together toasted pecans, brown sugar, and cinnamon; sprinkle over batter. Spoon in remaining batter over pecan mixture. Sprinkle with Pecan Streussel.
Bake at 325 degrees for 1 hour 20 minutes to 1 hour 30 minutes or until a long wodden pick inserted in center comes out clean. Cool in pan on wire rack 10 - 15 minutes. Remove from pan to wire rack, and cook completely (about 1 hour).