Sometimes people don’t realize the importance of using sound deadening material to improve the sound quality. I am not sure if you have noticed it but when you listen to music, it always sounds better when the music is louder. The reason behind it is sound pressure is a relative thing. By making the music louder, you have made the sound louder than the environmental noise. More detail in the music is then able to be heard and it makes people feel that it sounds better. Sound deadening material actually works in a similar way. But instead of working on the equipment, it works on the environment to be heard. Especially in a car, you get all kinds of noise from the engine, road noise and traffic. But for economic reasons not every car is built quiet. So by adding dampening material in key places you will be able to quiet down the car and thus make the sound quality better without cranking up the volume.

Another key reason is because loudspeakers are usually mounted on the metal panel of the door. A thin layer of metal is very prone to resonance and vibration. So when a speaker is bolted on, it will act like a part of speaker but in a bad way. The door would make all kinds of noise and degrade the clarity of sound especially in the mid to low frequency range (i.e. male vocal). That’s why it’s always a good idea to put sufficient amount of damping material around where the loudspeakers are installed to make sure there is minimal amount of noise when the music is playing. In fact, sometimes it would improve the sound quality so much it’s like you have different set of speakers.

So don’t spend too much money only on high power amplifier or high power handling speaker. Save some budget on the sound damping material and get ready to be surprised.