Rockford Fosgate P400-4

The Rockford Fosgate P400-4 is a middle-end car amplifier. It is a variation of the P400-2, and as such as all the same features. The only difference between the two is the number of speaker channels; the P400-4 has four, while the P400-2 only has two.

This gives it superior audio compared to the P400-2. The P400-4 features NOMAD technology, which uses an analog computer to prevent shorting out the speaker wires. It achieves this by calculating in real time the device voltage and current, activating a protection circuit when it senses things are dangerous. The P400-4 also features DSM technology, which improves the efficiency of the circuits. It manages this by laser etched discrete components. This gives the components a 1% tight-tolerance, which decreases cross-talk between the components, thus improving the efficiency of the circuits, as well as lowering the operating temperature.