You probably look at the tasteful, soft-focus pictures and think “Christ, I’d wondered what happened to Guy and Ralna from The Lawrence Welk Show.” But don’t be fooled: Unlike that now-divorced husband-and-wife singing duo, Al Petteway and Amy White are not only really and truly in love with each other—an energy that ricochets between them during their performances—they’re also in love with creating their caffeinated, jazz-spiked acoustic brew. Appropriately enough, these lovers are natives of Northern Virginia. Al played bass in local funk bands in the late ’70s, had a conversion experience after hearing John Renbourn at the Birchmere in the ’80s, and became a virtuoso of Celtic-style finger-picked guitar with a world-class reputation and a lengthy discography. Amy, a gifted visual artist, kept her music to herself until she met Al in 1994. Since then, he’s helped her find the nerve to play her compositions for other people (her album of piano reveries, Bittersweet: An American Romance, was recorded partly at tonight’s venue in 1998). Meanwhile, Amy’s background in classical music and improvisational jazz has stretched Al’s repertoire, as evidenced on the first album to bear both their names, 1999’s Racing Hearts. That project split their musical road into a tangle of possible paths. The one they’ve chosen to follow next will be featured on an upcoming album of “groove-oriented guitar duets” and, most likely, at tonight’s show. Watch Al and Amy groove together at 8 p.m. Saturday, July 8, at Harmony Hall Regional Center’s Addison Concert Hall, 10701 Livingston Road, Fort Washington. $12. (301) 203-6070. (Pamela Murray Winters)