To give life to your audio system you need to increase the power, it will let your music play louder and add definition to the nuances in your audio.
Amplifiers can loosely be split into 3 categories: full-range amplifiers designed for powering speakers, mono amplifiers producing just one powerful output channel for operating a subwoofer, or system amplifiers that have outputs for both speakers and subwoofers all in one unit. Of course there are exceptions to this but hopefully this gives a start of where to look for the amplifier you need.
A word of caution, amplifiers can massively increase the power going into your woofers. If you are inserting an amplifier into your system it is important to ensure you have the correct speakers and subwoofers that match the amplifier so nothing gets damaged. If you are in any doubt it is best to speak to a professional who can advise what works with what.