Car Audio Settings - HPF vs. LPF?

since that amp doesn't have a HPF ... i am guessing you are talking in your radio. set the HPF for your door speakers around 100hz- 125hz and the low pass filter on your sub out around 80-100hz...you can play with it to see what sounds best to you.

personally i would use LPF and adjust it from there (frequency cutoff and gain)

to maximize clean signal strength from your amp, you need to adjust the gain or input sensitivity settings. Here's how:

Set the input sensitivity controls of your amplifier to their minimum level (counter clockwise).

Put in a CD and turn the receiver's volume control up (you might have to raise the amp's gain just a bit to hear the music).

When you hear distortion, stop. Turn the volume down until it disappears. As much signal as possible is passing from the receiver to the amp. This maximizes the signal-to-noise ratio, and leaves your system less prone to engine noise problems. Keep the volume setting here.

Now turn the gain controls on the amplifier up until it's as loud as you'll play it. If you hear distortion, slightly decrease the gain settings.

Now you've optimized the amp's output with the receiver's volume set near maximum. You can turn the volume almost all the way up and not damage your speakers or amplify distortion. If you're hooking up a subwoofer, a test disc (or bass-heavy CD) is helpful for making final adjustments.