JVC Compact 4 Channel Amplifier The KS-DR1004D is a versatile amplifier designed for performance in harsh conditions thanks to its conformal coated main PCBs (printed circuit boards) that offer additional protection against moisture and condensation from damaging the product. This isn’t all that’s on offer with the KS-DR1004D, this compact amp is a proverbial work horse with an extensive range of features. The large LPF coil provides stable, high quality sound with no distortion even when playing at high volume. Separated circuit boards of the Pre-amp and Power-amp sections contribute to a reduction in radiation noise. A conformal coating is a protective chemical coating to safeguard electronic circuits from harsh environments that may contain moisture or chemical contaminants. It provides a barrier to airborne contaminants from the operating environment, such as salt-spray, thus preventing corrosion.