While paging back through the history of jazz, you can count the truly innovative who've played vibes on one hand. There's hall-of-famer Lionel Hampton, natch, Milt Jackson of the Modern Jazz Quartet, plus modernists Gary Burton and Bobby Hutcherson. With the arrival of the New Millennium and all, however, it's time to update the list. At the tender age of 31, Stefon Harris already has pocketed three Grammy nominations, consorted with icons (Wynton Marsalis) and written an ambitious 11-movement long-form piece that blends bits of classical, Africa and, of course, jazz (The Grand Unification Theory). When Harris lands at Stewart Theatre on Saturday, April 17, he'll bring his acoustic quartet, co-starring Marc Cary, a virtuoso pianist cosmically influenced by Keith Jarrett. The repertoire will touch all the bases--from naughty blues to familiar standards to excerpts from his forthcoming Blue Note disc Blackout, a tasteful foray into butt-waggin' jazz-rock territory. To prep for the show, check out Harris' sleek Web site stefonharris.com and/or consider a pre-show discussion led by N.C.-based vibes maestro Jon Metzger. Dial 515-1100 for details.