Simply put, King's X is a marvel. The Katy-based trio has been hanging around the margins of hard rock for nearly 30 years; next year marks the 20th anniversary of Gretchen Goes to Nebraska ("Summerland," "Over My Head"), one of the pivotal albums of the high Headbanger's Ball years. Though never quite breaking through to a mass audience, the band didn't have to make the kinds of compromises that go hand-in-hand with reaching such a level — such as dumbing down its intensely spiritual lyrics — and has never disappointed its intensely loyal following. The hometown chapter of that following was out in force for King's X's last Meridian show this past August, where dUg Pinnick, Ty Tabor and Jerry Gaskill more or less blew Extreme off the stage with a searing set that showed how little drop-off in quality there's been from 1988 debut Out of the Silent Planet through this year's XV — i.e., none. Pouring blues, funk, prog and the Beatles into a metallic drill-press and doling it out one steamroller riff at a time, "King's X put on a clinic in sleek, soulful Texas hard rock," we wrote at the time. Now that they're freed from the confines of an opening slot, expect Saturday to be a full-on doctoral seminar in the same.