Welcome home, Leroy: the premier postfreedom violinist hasn't played his hometown in six or seven years, during which time he has led bands both acoustic and electric and recorded surprisingly little. No band, though, has matched Jenkins's cooperative trio of the 70s, the Revolutionary Ensemble, when it comes to showcasing his blunt and often startling solo style. Some jazz historians have zeroed in on Jenkins's application of new-music techniques to create sounds--scratches, creaks, musical squeals--previously unheard on the jazz violin, and that's all well and good. But I find the contours of his improvisations, and the tone that carries them to the listener, far more noteworthy. His solos fly free of harmonic constraints and predetermined formal barriers, though Jenkins occasionally reins them in by pursuing nuggets of melody with a minimalist's care. He also grounds his lines in simple, straightforward rhythms, which imparts a strong folk-music element to much of what he plays. As for his tone, it has a rough edge but a concertmaster's heart; in that respect at least, you can view Jenkins as a very modern successor to Stuff Smith (the exuberant jazz violinist who in the 1930s became the first to play an amplified instrument). And, what the hell, I'll take it a little further. I see Jenkins as the only postbop player to successfully combine the two basic schools of jazz violin--the raucously swinging style established by Joe Venuti and the elegantly refined style created by Stephane Grappelli--even though he works in an idiom foreign to them both. Few improvising violinists could handle the rigors of performing without accompaniment, as Jenkins will tonight. His early work with the Association for the Advancement of Creative Musicians, which once required all members to present solo concerts, should come in handy. Friday, 9:30 PM, HotHouse, 1565 N. Milwaukee; 235-2334.