Adding an amplifier or subwoofer to a Subaru with Harman Kardon

Why the Harman Kardon system is different

In a Subaru with the Harman Kardon audio package, the factory amplifier and the factory radio are closely linked. The amplifier — not the radio — controls balance, fade and volume. That single fact drives every decision on this page: if you remove or bypass the amplifier without replacing what it does, you lose volume control.

It also means you cannot simply run audio into the factory amplifier and expect it to work. There is communication between the factory radio and the Harman Kardon amp, so the amp will not switch on just because it is receiving an audio signal.

These systems run eight speaker channels, not four. Anyone planning an aftermarket amplifier needs to account for that before buying.

Route 1 — keep the Harman Kardon amplifier, add your own amp downstream

This is the approach we use most often, and the one that keeps the factory system intact. You daisy-chain the new amplifier or processor from the output of the factory amplifier. The Harman Kardon amp stays installed, so you keep volume, balance and fade.

We build a 30-pin Harman Kardon amplifier jumper harness for this. It plugs in between the factory harness and the amplifier — no factory wires are cut — and gives you access to the speaker signals plus power wiring for an aftermarket amplifier. You cut the wires from the adapter for the channels you want to use: one side feeds the input of your new amp, the other side carries the output back out to the speakers.

Route 2 — replace the factory amplifier

If you would rather remove the Harman Kardon amp entirely, you need something to take over what it was doing. Two options we have used:

• iDatalink Maestro RR2 with the HRN-RR-SU3 harness. Retains the amplifier and the steering wheel controls, and is what we recommend when someone is replacing the radio at the same time. It is programmed over USB using your new radio's serial number — send us the serial and we will do it for you.
• Rockford Fosgate DSR-1. Interfaces with the factory radio and lets you replace the amplifier with an aftermarket one. It has a built-in DSP, so most of the tuning you would want to do happens in its app.

If you are keeping the factory radio

Perfectly possible, and it changes the job considerably. Upgrading only the amplifier on a Harman Kardon car needs components that can interface with whatever amplifier you choose — this is not a case where you can swap the amp and be done.