Once you have installed your amp and subwoofer, it’s time to configure the sound. In order to get the optimal bass settings for your personal taste, I recommend you use a favorite song. By picking a song that you are very familiar with, you can fine tune the sound to match the way you think it should sound. If you like various styles of music, you may want to test them all to see what works best. You’d be surprised how much of a difference it makes between hip hop and classic rock, because one uses a lot of resonating bass sounds while the other has more punch type bass from bass drum kicks.
You should always start by turning all the volume levels on the amp to zero. Get it out of your head that louder is better, because if you crank up the gain too much you will end up with muddy sounding bass that flutters instead of thumps and distortion that ruins the sound. Play your song at your usual listening volume, then slowly turn up the gain on the subwoofer until the bass starts to hit like you want. You want the bass to be clean and the sub should not rattle inside the box. Keep turning it up until you hear distortion, then turn it back down a notch.
Some stereo head units have individual subwoofer volume controls, so you may want to adjust it as well as the amp volume. There are too many different types of configurations to discuss here, but the basic idea is to turn it up until it starts to sound bad, then turn it back down a little. You’re looking for that sweet spot where it hits really well and still sounds good. If your amp has a crossover or bass boost feature, those are more knobs you’ll need to play with.
The end result of all the adjustments is that you should be able to turn your stereo volume up as loud as you can possibly stand it and the sound still remain clean. Don’t turn it up as loud as it will go, because it will surely not sound good. What’s important is that your usual listening volume sounds good to you.