Hiatt and Colvin celebrate the finest singer-songwriter tradition

John Hiatt, Shawn Colvin

AT Charter One Pavilion

A double bill of folkie Shawn Colvin and rootsy, Americana-inspired troubadour John Hiatt might appear to be too similar apairing, especially with both scheduled to perform solo, brandishingonly acoustic guitars (and, in Hiatt's case, a keyboard on severalsongs). But Wednesday night at the Charter One Pavilion on NortherlyIsland, the two veterans played sonic counterpoints and unveiled, forthe midsized but adoring crowd, unique performing styles thatcomplimented and enriched each other's sets.

If Hiatt's almost two-hour show (he was the official headliner)was like a stiff drink of whiskey, burning as it went down …