The amount of continuous power, measured in watts, that an amplifier produces is called RMS power. The higher the RMS figure, the louder and cleaner your music sounds.
Some amps include circuitry that allows you to boost the bass output, ranging from a knob or button that provides a set amount of boost, to a built-in parametric equalizer with many possible configurations and adjustments.
Preamp outputs are RCA outputs that let you pass the preamp audio signal from one amp to additional amplifiers.
Useful if you're adding an amp to a factory radio, or don't have enough preamp outputs on your aftermarket receiver. Speaker Level Input Types: Harness, Speaker Terminal, RCA.
Each amplifier "class" has different performance characteristics, determined by its internal circuitry:
Class A amplifiers are desirable for the high quality of their sound, but, because of the configuration of its transistors, a pure class A amplifier is inefficient and runs very hot.
By far the most common car amp design, Class AB amps run cooler, and therefore, more efficiently than a class A, with low distortion and high reliability.
Class D amps (usually used to power subwoofers) boast higher efficiency, produce less heat, and draw less current than Class AB amps. Class D amps produce higher distortion, but this distortion occurs at high frequencies that are typically removed by a low-pass filter and is therefore inaudible.
Class BD amps give you the super-efficient design of a Class D amp with the clarity and sound quality of a Class B amp.
Minimum Impedance Unbridged
The lowest impedance the amplifier will handle when it is in unbridged mode.