The tour in March 1987[citation needed] of Knuckles, Jefferson, Fingers Inc. (Heard) and Adonis as the DJ International Tour boosted house in the UK. Following the number-one success of MARRS' "Pump Up The Volume" in October, the years 1987 to 1989 also saw UK acts such as The Beatmasters, Krush, Coldcut, Yazz, Bomb The Bass, S-Express, and Italy's Black Box opening the doors to a house music onslaught on the UK charts. Early British house music quickly set itself apart from the original Chicago house sound;[citation needed] many of the early hits were based on sample montage, rap was often used for vocals (far more than in the US),[citation needed] and humor was frequently an important element.