As integral to Howlin' Wolf's classic Chicago sound as Wolf's own roaring vocals and spellbinding emotional intensity was the guitar of Hubert Sumlin. Characterized by a slashing, staccato chording style and flights of imaginative fancy as distinctive and unpredictable as any in blues guitar history, Hubert's leads inspired Eric Clapton and countless others to explore the rich lode of improvisational possibilities beneath the deceptively simple three-chord structure of the blues. Hubert is a gentle, kindly man of deep emotional complexity; the same idiosyncratic vision that gives birth to his unique melodic ideas has been known to result in wildly uneven sets, brilliant one moment and near-chaotic the next. The last few times I've seen him, however, he's been solidly on; his mind has lost none of its delightfully eccentric melodic playfulness, and in his guitar playing is the soul of one of the most seminal popular music styles of the 20th century. Wednesday, B.L.U.E.S., 2519 N. Halsted; 528-1012.