What Steely Dan did in the mid-'70s was upscale rock and roll by suffusing it with the vocabulary of bop. Their Monkish tunes -- "Haitian Divorce," "Deacon Blues," and the sultry "Rikki Don't Lose That Number" -- were burned into millions of brainpans during that medicated decade, for good reasons. The band offered Becker's choppy guitar; Fagen's steely, soulful vocals; arrangements that were always crisp, unexpected, and formally impeccable; and lyrics that, at best, were thought-provoking, even titillating. Becker and Fagen have had enough differences over the years to keep them from working frequently as Steely Dan, by far their most successful vehicle. Becker has released some solo works; Fagen was more successful with his solo ventures, The Nightfly and Kamakiriad. Together, they've been rare (they last toured as Steely Dan in 1993, though they've worked together in other formats), so their Blossom date should be fascinating. Or at least instructive in how oddball, aging rock stars can -- or can't -- reclaim an audience that, particularly in the classic rock hotbed of northern Ohio, is likely to turn out in force.