To some — and I would count myself among them, until a few years ago — Steely Dan is essentially audio Teflon: an impenetrably slick surface to which nothing sticks, including the listener’s interest. (I won’t out the co-worker who poked her head into my office when she heard “Kid Charlemagne” and said, “Are you having a white-guy barbecue?”) But there is slickness that deflects scrutiny and slickness that makes the barbs sink in deeper, and if you always assumed Steely Dan embodied the former, listen beyond those sinuous melodies and impeccably executed arrangements — smooth as the silk in a yacht rocker’s drawers — and you’ll hear they’re really the latter. I don’t know what threw the switch for me: the creeping menace that powers the infernally catchy “Showbiz Kids,” maybe, or the line, “They got a name for the winners in the world / I want a name when I lose / They call Alabama the Crimson Tide / Call me Deacon Blues.” But the fact is that Walter Becker and Donald Fagen assembled some of the most technically gifted players ever to record music — a few of whom might be in the audience tonight — and put them at the service of their jaded-observer sensibility, coolly cutting lyrics and the needed tartness of Fagen’s lemon-sucking vocals. Which is to say they’re a lot better than they sound, and they sound great. We hope show security is tight — one mishap in the crowd could wipe out every session cat in Nashville.