Most classical music enthusiasts are aware that the Dallas Symphony has elevated itself over the last decade or so to a position in the top ranks of American orchestras. But toiling in the shadow of Dallas is another outstanding ensemble that usually gets mentioned in the national press only as the resident orchestra for the Van Cliburn piano competition. Once a regional chamber orchestra, the Fort Worth Symphony has thrived under the leadership of music director Miguel Harth-Bedoya, and William Littler says that the group deserves to be taken seriously in any discussion of North America’s top orchestras.