Steely Dan, Tuesday, September 6, at Fiddler's Green, is a legendary act, and the chance to see the band live is a rare treat indeed. Walter Becker and Donald Fagen achieved breakthrough success in 1973 with the album Can't Buy a Thrill, but quit playing concerts the next year. Fortunately, that didn't stop the Dans from putting out a handful of additional releases that were filled with superb, jazzy rock. Following Gaucho, released in 1980, the duo decided to pursue separate interests: Becker went on to become an extraordinary producer, while Fagen became a choice freelancer in the print media as well as the creator of several top-notch solo efforts. The pair finally reunited last fall, but there's no guessing how long they'll stay together. Catch their complex and innovative sounds now, before they disappear again.