The PA D4000.4 is Polk Audio's new high-efficient digital 4-channel amplifier. This amplifier is perfect for providing the correct amount of power to a complete four speaker upgrade to your car audio system. The ability to bridge channels will give you more options on amplifying other applications such as subwoofers. This 4-channel can do amplify anything from high-end speakers to 4 entry level subwoofers. 

Features

• Super-efficient Class D design runs much cooler than conventional amps
• High-speed MOSFET switching power supply
• Toroidal transformers help keep the amplifier’s sleek design under 2 inches tall while ensuring plenty of clean, efficient power
• Protection: Thermal, DC offset, reverse DC voltage and short circuit protection
• Nickel-plated wire terminals and RCA connectors ensure maximum signal transfer
• Front and Rear Level Controls—Adjust the gain of the front and rear channels to match the output voltage from your head unit
• Low-Pass and High-Pass Frequency Controls—enables you to adjust crossover overlap for better blending of speakers
• Front and Rear BPF, FULL, HPF Switches— Selects full range, high pass filter, or band-pass filter to dial in your speaker blending
• Channel Mode Switch (ST/4Ch)— In the Stereo position, the amplifier will send the same signal to front and rear channels
• Stainless steel hardware used throughout won’t corrode in humid environments