В смешении джаза и рэпа. В качестве примера послушай Guru's Jazzmatazz Vol.1.

На allmusic.com джаз-рэп описан так:

Jazz-Rap was an attempt to fuse African-American music of the past with a newly dominant form of the present, paying tribute to and reinvigorating the former while expanding the horizons of the latter. While the rhythms of jazz-rap came entirely from hip-hop, the samples and sonic textures were drawn mainly from cool jazz, soul-jazz, and hard bop. It was cooler and more cerebral than other styles of hip-hop, and many of its artists displayed an Afrocentric political consciousness, complementing the style's historical awareness. Given its more intellectual bent, it's not surprising that jazz-rap never really caught on as a street favorite, but then it wasn't meant to. Jazz-rap styled itself as a more positive alternative to the hardcore/gangsta movement taking over rap's mainstream at the dawn of the '90s, and concerned itself with spreading hip-hop to listeners unable to embrace or identify with the music's increasing inner-city aggression. As such, jazz-rap found its main audiences in places like college campuses, and was also embraced by a number of critics and white alternative rock fans. Afrika Bambaataa's Native Tongues posse — a loose collective of New York-based, Afrocentric rap groups — was the most important force in jazz-rap, including groups like A Tribe Called Quest, De La Soul and the Jungle Brothers; Digable Planets and Gang Starr were other notable early artists. During the mid- to late '90s, as alternative rap moved into a wider-ranging eclecticism, jazz-rap was not often pursued as an exclusive end, although the Roots frequently incorporated it in their live-instrumentation hip-hop.

Для уважаеющего себя джаз-рэппера использование минусов самом по себе - вещь неприемлемая (это вовсе не камень в огород A Tribe Called Quest или De La Soul - у них просто вряд ли были средства на живой инструментал). Правильный джаз-рэп записывается живьём.