I have used many audio system.Here is my experience for maintaining the speakers so that they give the same quality of output as when you bought it.
First thing is choose an audio system according to your need, according to the amplification you need and the interface if you connect. Otherwise you might face problems in its sound quality.
If you are using interface then please use a good quality interface or the uneven frequencies from it will affect your speakers.
Avoid magnet stuffs from reaching nearby speakers, or the electromagnet inside will damage.
Be sure that the speakers remain dust free because the dust affects the quality of sound, so clean on every do alternate day and yes do not use any cleansing formula very often.
Do not exceed the amplification limit for which the speaker is suitable of. Like if you increase the volume in cheap speakers you will find it distorted.
Follow these steps and you’ll see a increase in the life of your Audio system.