In the frequency range where drivers operate in a nearfield line array, they are omnidirectional. So the angle of the driver will not make a difference. However the driver will interact with the baffle edges, the steps will make a difference there. On a large flat baffle a driver's wavefront is a coherent semi-shphere. When the wavefront encounters an edge of the baffle it defracts causing interference. This should be taken into account when designing any speaker. On a stepped baffle it will be more significant than a simple box. There will be interference above and below each driver, not only from the adjacent edges but also from the edges further away from each driver.