Tenor sax legend Lou Donaldson strolled out cool and casual onto the Kilbourn stage in a black suit promising nothing but straight-up jazz. “No fusion, no confusion,” he said. He and his quartet then launched into a sweet take on his 1957 “Blues Walk” where he let Akiko Tsuruga, the little lady behind the B3, swell, swirl, and swing. By the time they were into the second tune — essentially a Charlie Parker piece, even though according to Donaldson, Bird stole it — the guitarist was playing so fast he almost fell off his stool. At 81 Donaldson still exhibits incredible tone and seemingly effortless phrasing. He comes from the hard-bop school, and with this early set he proved to be its headmaster. Pure jazz with enough hairpin turns to keep it interesting, and a few straight-aways to lure the rookies…