If you want to get the maximum performance from your loudspeakers and subwoofers, definitely add a Polk PA D amplifier or two. We offer 2-channel, 4-channel, 5-channel and monoblocks. Each PA amp is styled lean and plays meaner, with enough big, fat juicy watts to drive your system so you get to hear all of your music, no matter where and how loud you like to play.

PA D4000.4 4 Channel Amplifier

Super efficient class D bridgable 4-channel mobile audio amplifier

The PA D4000.4 amplifier is capable of bridging two full-range channels into a single full range channel with higher output power. For instance, one front and one rear channel will increase the output power from 125W per channel to 400W per channel (for a 4 ohm load). The most common hookups for the PA D4000.4 would be four full-range channels, two full-range channels and a bridged sub, or two bridged subwoofers.

RRP $649.00 AUD

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-inch tall while ensuring plenty of clean, efficient power.

Protection—Thermal, DC offset, reverse DC voltage and short circuit protection.

Nickel-plated wire terminals & RCA connectors—Ensure maximum signal transfer.

Front & rear level controls—Adjust the gain of the front and rear channels to match the output voltage from your head unit.

Low-pass & high-pass frequency controls—Enables you to adjust crossover overlap for better blending of speakers.

Front & rear BPF, FULL, HPF switches—Selects full range, high pass filter, or bandpass 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.


Total Frequency Response 20Hz-20kHz 
Signal-to-noise (Referenced to rated power) 105 dBA
Distortion at Rated Power <0.1 %
Minimum Impedance Bridged 4 ohms
Minimum Impedance Not Bridged 2 ohms
Protection Circuitry Thermal, DC offset, reverse DC voltage and short circuit; fuses: one 40 Amp and one 35 Amp ATC 
High Pass Filter
Filter Slope 12dB/octave 
Filter Frequency 20Hz-4kHz (front)/20Hz-4kHz(rear) 
Low Pass Filter
Filter Slope 12dB/octave 
Filter Frequency 50Hz-5kHz(front)/50Hz-5kHz(rear) 
Effective Damping Factor >100 
Max Sensitivity 200mV-6V dB


Cabinet Dimensions
Height 1 13/16" (4.60cm) 
Width 10 15/16" (27.78cm) 
Depth 6 3/4" (17.14cm) 
Product Weight (each) 5.0 lbs. pounds
Without Panels
Height 1 13/16" (4.60cm) 
Width 10 15/16" (27.78cm) 
Depth 6 3/4" (17.14cm) 

Amplifier Specs

Channel Notes Bridgeable Class D MOSFET 
12V & Ground Cable Gauge 4AWG 

Amplifier Power Specs

RMS Power at 14.4V
Watts per channel NOT bridged @ 1 kHz
4 ohms 125 watts
2 ohms 200 watts
Watts per channel bridged
4 ohms 400 watts