Unfiltered and unplugged, Aaron Lewis descends on D.C.’s Warner Theatre next Thursday night, toting only his acoustic guitar. The no-strings format seems wildly appropriate for Lewis, who has gained notoriety by bringing hard rock group Staind to the forefront of the music world. Raised in Massachusetts, where he still resides today, Lewis is indelibly etched from the everyman mold and still celebrates the simple things. The acoutriments of fame are all well and good, but Lewis is as grounded as ever.