A device designed to boost the signal strength from a source unit (such as a head unit or aftermarket radio) to an amplifier is commonly used in vehicle sound systems. This amplification improves audio quality by reducing noise and distortion introduced by long cable runs or weak source signals. For instance, if a factory car stereo outputs a weak signal, this device can bolster it to a level suitable for driving a powerful aftermarket amplifier.
Utilizing such a device offers several advantages, including cleaner audio output, improved signal-to-noise ratio, and compatibility with a wider range of amplifiers. Historically, these devices have played a critical role in achieving high-fidelity audio in car environments, especially before head units with robust preamp outputs became commonplace. They continue to be valuable for integrating aftermarket equipment with factory systems or overcoming limitations in older vehicles.