IF YOU DIDN'T KNOW Adagio Trio was from Chesapeake, after listening to "Celtic Heart" you'd swear the group was from the enchanting misty coastlines of Scotland or Ireland. That the trio is so convincing is no small feat. The 16-song CD is its first all-Celtic album, and it is, in a word, beautiful.  Adagio Trio consists of harpist Linda Grieser, flutist Kathryn Daniels and cellist Michael Daniels. Grieser and the Daniels family duo formed the group in 1985 when they lived in Cincinnati. Five years later the Danielses moved to Norfolk when Michael accepted the co-principal cellist position with the Virginia Symphony Orchestra.  In 1997 the trio released its debut album, "Stillpoint," an eclectic and tranquil blend of religious, folk and classical music. The formula was replicated on 1999's "Sanctuary" and 2005's "Evensong." An album of Christmas classics, "Winter Gift," was unwrapped in 2002.  A common thread that runs through each Adagio Trio recording is a soothing repertoire that flows as effortlessly and gently as a mountain stream.  "Celtic Heart" features a menu of traditional fare ranging from the obligatory "Danny Boy" and "Roslyn Castle" to the haunting "Chanter" and peaceful "Christ Child's Lullaby." The overall production is crisp and clear.  The rare jig ("Morrison's Jig") and reel ("Joe Cooley's Reel") selections, generally played as lively dance pieces, are arranged in the same subdued balladry style as the other works and provide an even-tempo consistency that is quite nice. Especially pleasing is the beautiful melody of "Skye Boat Song," a masterful example of the trio's interplay.  Throughout "Celtic Heart," Adagio Trio proves that the quieter side of Celtic music is an equal companion to the familiar blaring rounds of bagpipes and Riverdancelike frolicking.