Multichannel audio systems always need large numbers of loudspeakers and special placement, or sometimes need many subject evaluations to find an optimal arrangement. The application of multichannel systems is difficult in a typical home environment, where few number of loudspeakers, few subject evaluations and the placement flexibility are highly desirable.In this paper, a design of convex polyhedral loudspeaker arrays surround the target region is proposed for reducing multichannel system adaptively, and then derive an error metric to narrow down the subjective evaluation list. In such a way, a well-performed loudspeaker arrangement can be chosen by few subjective evaluations and placed in a restricted environment. The reproduction accuracy of the method is verified through numerical simulations, and the subjective evaluations indicate the effectiveness of the method.