Britain's Olympic hopefuls beat the USA 4-1 at York Hall to extend their unbeaten run to four fixtures.
British Lionhearts super-heavyweight Joe Joyce won with a stoppage of Brandon Lynch and flyweight Muhammad Ali beat Gaurav Bidhuri on points.
Joseph Cordina was an emphatic winner over lightweight Bruce Carrington.
Welterweight Cyrus Pattinson lost to Andreal Holmes for the USA's only point but light-heavyweight Joshua Buatsi beat Souliman Abdourachidov.
The World Series of Boxing serves as a route to Rio 2016, with British fighters who represent the Lionhearts eligible for selection for an Olympic qualifying event in May.