A Tribe Called Quest were always a favorite with those who prefer their hip-hop intelligent and innovative; and Q-Tip, a founding member in 1988 and effectively the group’s leader, seemed like he might have held the keys to hip-hop’s full potential.He appeared on fellow Native Tongues Posse rappers De La Soul’s innovative 3 Feet High and Rising (1989), and made four progressive albums with A Tribe Called Quest before the group disbanded in 1998. Although his first solo project, Amplified, went gold, it wasn’t the giant step forward it could have been.Fortunately, Kamaal the Abstract is. Q-Tip (or Kamaal, as he now wishes to be known) still raps, but he devotes more energy to acting as vocalist, musical director and producer on this new and heady genre fusion. Jazz — the last word in class and sophistication in progressive rap and soul circles — is more pronounced than ever before, provided here by Gary Thomas and Kenny Garrett (both former Miles Davis sidemen). Thomas plays flute over the lovely, loping, start-stop groove of “Do U Dig U?” and gets pretty abstract himself. Garrett — Davis’s last great find and possibly the most exciting alto saxophonist in the world — blows through “Abstractionisms,” otherwise one of the closest tracks to orthodox rap found on the album.Everything here is soft and loose. A long organ solo files down the rough edges on “Feelin’, ” turning it into smooth, comfortable soul jazz. Funky electric piano does a similar trick with “A Million Times,” and the soulful “Blue Girl” ends with an acoustic piano solo.There are few high or low moments — which might put some listeners off — but texture and content, rather than pulse-raising histrionics, have always been Q-Tip specialties.