1987 saw the introduction of the grand touring series of amplifiers, beginning with the gta. its successor, the gtb, came out the next year. this model line, designed for the road and known for its rugged durability and conservative power rating, was adopted by many concert sound companies, some of whom became bgw dealers. wachner himself visited these dealers, flying around the united states in his private airplane to meet them. his interaction with the sound reinforcement system company owners and operators led to wachner's work on signal processing in conjunction with amplifier power in order to achieve flat power response in multi-band sound systems; a paper given to aes in may 1988.