The faddish days of like-instrumented ensembles--tuba trios, kazoo quartets, Casio quintets--are hopefully now past. What's left are a few resilient ensembles, especially those still at work in the fruitful saxophone-quartet genre. Given the variety of tonal, rhythmic, and textural possibilities open to reed players, it's easy to forget that a sax quartet operates on one basic ax, particularly when the pads are hot under creative fingers in quartets like ROVA, World, and 29th Street. Your Neighborhood Saxophone Quartet, from Boston, hasn't received as much ink as those bands, though it's been around since 1980 and has recorded six albums. Maybe the name damns it to eternal local status, but if there's any justice its first midwest tour should open up some ears in the Chicago 'hood. YNSQ is less angular and scronky than ROVA, though just as inventive; it's less blues-dependent than WSQ, though every bit as slinky. The group's newest CD, Wolftone (Coppens), sports full arrangements of Duke Ellington and Hermeto Pascoal, as well as relaxed, lyrical originals like baritonist Tom Hall's Latin-tinged "El Cambio," tenorman Joel Springer's terse, big-bandish "Midwestern," and alto/sopranist Allan Chase's appropriately loopy "Saturn's Rings." Plutonian Nights (Coppens), the quartet's critically acclaimed 1993 record, features retooled versions of music by Saturn's own Sun Ra. In fact, Chase is one of the world's great Ra cognoscenti, having written his master's thesis on the supersonic man. Not likely to rip the house down, YNSQ has a refined approach, combining melodic and harmonic subtlety with expansive, at times chamberlike sensibilities. But the members can slip into a funky space, as they do on Hall's blowing vehicle "P22," and even their airier, sprightlier tunes have a devilishness about them. Saturday, 8 PM, Green Mill, 4802 N. Broadway; 878-5552.