Was the rap group playing with a live band? Or was the bass a sample they played on a loop?
Most rap acts that I have seen use only a DJ but the rappers I have seen with a live band:
Common this past August played a full band. Bass, guitar, 2 keys, drummer, flute and multiple vocalists. J. Cole was a guest and played about 4 songs.
Last night Vic Mensa (Chicago) played with a 2 person band (one dude on keys and the other on guitar, drum machine, sampler) and he opened for JayZ who played with a full live band which included two drummers and AT LEAST 2 keyboards. They were hard to see as it was a round center stage and then were recessed into the stage and in one of four pods.
OC: My Tinybox seemed to do OK given the organ shattering bass during some of Mr. Carter's tunes.