You don’t see Brad Williams’s name on the marquee very often. He’s made himself so valuable an accompanist–not only to Chicago artists (Von Freeman, singers Jackie Allen and Kirsten Gustafson) but also to visiting dignitaries (such as vocalist Sheila Jordan, who sings his praises whenever she can)–that you almost forget his ability to lead a trio on his own. Almost, but not quite: even when serving as an accompanist, his fluent touch and brainstorming improvisations invariably place him in a starring role before the first set ends. The myriad sideman gigs have instilled in Williams an undeniable sense of his keyboard: having shaped his music to the demands of so many others, he deservedly revels in his own versatility. But this wide-screen approach to piano jazz constitutes only the first and easiest approach to Williams’s playing, and you ignore the fine details–the interplay of light and dark, the unusual angles, the narrative contours–at your risk. Williams never fails to surprise and tickle. His debut album, The Next Sound You Hear, made a relaxed but impressive splash last spring, not least for his easy manipulation of the trio format; that he can further explore that microcosmic musical world on a regular basis means a lucky break for us as well as him. Wednesdays at 8 his trio performs at the Gold Star Sardine Bar, 680 N. Lake Shore Dr.; 664-4215. Next Friday, November 18, at 9 and Saturday, November 19, at 8 he accompanies Sheila Jordan at the Green Mill, 4802 N. Broadway; 878-5552.