A very useful circuit for those who built their own amplifiers. It will protect the speakers from overloading, DC, and other dangerous signals. It protects both channels at the same time and also connects the speakers with the amplifier a short time after the power is turned ON thus protecting the speakers from the "THUMP" that is usually heard and which can sometimes destroy your expensive speakers. Suitable power supply is the SMART KIT 1061. Operating voltage: 12VDC.