Prepare Beef: Slice the beef round into thin, even strips. Partially freezing the beef beforehand can make slicing easier.
Mix Marinade: In a bowl, combine soy sauce, Worcestershire sauce, brown sugar, smoked paprika, garlic powder, onion powder, black pepper, and cayenne pepper.
Marinate Beef: Place the beef strips in the marinade, ensuring they are completely covered. Refrigerate and marinate for at least 4 hours, preferably overnight.
Preheat Smoker: Preheat your smoker to 160°F (71°C). Add your choice of wood chips to the smoker.
Smoke Beef: Arrange the marinated beef strips on the smoker racks. Smoke for 4 to 6 hours, or until the jerky is dry but still pliable.
Cool and Store: Remove the jerky from the smoker and let it cool completely before storing in an airtight container.