What did your dual 15 inch stereo used to do? Under normal circumstances, 150-200 square meters of general wedding or outdoor advertising stage sound, double 15 inch speakers is enough. If it is used outdoors, it is suggested that the power of the amplifier is twice that of the speaker, and the effect will be better. However, the formal stage performance is much worse, and it needs to be equipped with special low speakers to show the effect.