I found them! If ABBA were reincarnated as a country group, they would be Little Big Town! Two guys and two girls! A brunette and a blonde. Dark-haired Karen Fairchild sings low. Blonde Kimberly Schlapman sings high. Jimi Westbrook and Phillip Sweet contribute to the four-part harmony that makes LBT so special. They have five albums dating back to 2002. They write most of their own material, and every song is a good one! "Pontoon" became their first number one single.