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This Model Has Been Discontinued


Amazing Power to Size Ratio


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In many of today’s installs, wattage per square inch is a deciding factor on what amplifier gets the job. For the D4.125, DD’s engineers were able to take the existing D4.100a’s compact chassis, which is only 7” x 4” x 1.7”, and increase the total output by 20%. The D4.125 can cleanly produce 200 watts per channel for a staggering 800 watts of total power. Beyond its amazing power to size ratio this amp is packed with features not normally seen on amplifiers in this size and price category.

The D4.125 also has conformal coated internal components and sealed back switches making it perfect for motorcycle, boat, and powersport applications. As if this amp didn’t have enough going for it, DD also has a line of made for Harley Davidson brackets that allow the D4.125 to cleanly and securely mount into 2014 and up Harley Road Glides and Street Glides.


  • Bandpass Crossovers
  • Clipping Indicators
  • Input Mode
  • Auto Turn On
  • Set Screw Power Connections
  • Set Screw Speaker Connections
  • Differential RCA Inputs
  • Discrete Outputs

D4.125: 800 Watt – 4 Channel Amplifier

Operating Voltage: 9 - 16
Test Voltage: 14.4
Output Channel(s): 4
Continuous Wattage @4ohm: 4 x 125 / 2 x 400
Continuous Wattage @2ohm: 4 x 200
Max Current Draw (Amps): 80
RCA Input Voltage Sensitivity: 8 - 0.2
RCA Input S/N: > 90dB
Damping Factor: > 100
THD: < 0.2%
Frequency Response (Hz): 30 - 30k
High Pass Filter: 30 - 5k
Low-Pass Filter: 50 - 5k
Pass Thru Output: No
Power Wire Gauge: 4
Speaker Wire Gauge: 12
Dimensions (Inches): 7 x 4 x 1.7
Dimensions (MM): 180 x 104 x 43
Price (USD): 429 each


If you’re looking for superior motorcycle audio solutions that sound as good on the highway as they do while you’re jammin’ out in the parking lot, we’ve got you covered. From amplifiers to speakers and DSP’s, these products are powerful enough to break through the roars of the ride to give direct, loud and clear sound.

Learn why these products are the superior choice for motorcycle audio solutions.

superior motorcycle audio with VO-W speakers with horn in saddle bags

The D Series amplifiers are designed to be the best amps on the market for the everyday mobile audio enthusiast.  These class D amplifiers feature compact chassis, superb sound quality, reliable circuits, and powerful output sections. They’re available in several channel and power configurations assuring there is a D Series amp to power your system.

Jabee Toyota Prius Loaded Enclosure Being Installed

Support Small Business and Enjoy Expert Installation

We believe in supporting brick and mortar dealers and have carefully partnered with small businesses who can provide quality installation and customer satisfaction befitting DD AUDIO® equipment.

Check with your local dealer for stock and promotional discounts.