[. . . ] If the power of the amplifier is higher than the subwoofer's rated input power, increase the number of subwoofers so that the power fed to each subwoofer is lower than its rated input power, or lower the sensitivity of the amplifier. [. . . ] Also, if using multiple subwoofers, be careful about the total impedance. Use a crossover network of your choice with an appropriate cut-off frequency. Water and moisture -- Do not install the speakers in locations which may be subject to water or moisture. Dust and unstable locations -- Do not install the speakers in unstable locations or locations subject to dust. â· When the volume is set too high, the sound may be distorted or abnormal. While the listening volume is set to a high level, do not load or eject a disc or cassette tape or operate the selector and power switches of the amplifier. Separate waste collection systems) Products with the symbol (crossed-out wheeled bin) cannot be disposed as household waste. Old electrical and electronic equipment should be recycled at a facility capable of handling these items and their waste byproducts. [. . . ] contact your local authority for details in locating a recycle facility nearest to you. [. . . ]