The Dallas Symphony Orchestra’s “Impromptu ticket program aims to fill empty seats while also giving time-starved music lovers the flexibility to catch a show on short notice. But rather than buying deeply discounted tickets online or through Web-based auctions, patrons would pay a monthly fee in exchange for getting the “best seat available” at the 2,056-seat Morton H. Meyerson Symphony Center – seats that went unsold or were turned back to DSO at the last minute by subscribers.”