Class D amplifiers are extremely efficient and high powered. Typically Class D amplifiers are monoblock amplifiers dedicated to providing efficient power to subwoofers, however there are some multi-channel class D amplifiers. 2-Channel amplifiers are designed to power to speakers. These amplifiers are perfect for powering a vehicle's front speakers or the back speakers. Select 2-channel amplifiers are also bridgeable, which allows them to be a great amp for powering a subwoofer. 2-Channel car amplifiers are also referred to as stereo amplifiers. Multi-channel amplifiers are designed to power 2-channels or more. These amplifiers are useful when specific amps are needed for a custom installation. Multi-channel amps allow for different configuration between channels and bridging of channels. Hope that helps bro.