A good-quality pro audio mixer can literally mean the difference between a successful event and an audio nightmare. If the levels are not correctly mixed, this can result in a "muddled" sound. Finding a good pro audio mixer can be difficult, however, especially if you happen to be on a budget. Cheaper models can tend to fail when you need them most, and many of the professional-grade models are extremely expensive. There are some great affordable mixers out there, you just have to know what to look for. It is a good idea to know some of the basics of amplification and sound mixing in order to get the absolute most out of your sound mixer. Electronic sound is produced when acoustic sounds, either through an instrument or a voice, are converted into an electric sound via a microphone or a pickup. This electric signal is then sent to an audio mixer.
The mixer is where all of the "coloring" of the particular sounds takes place. The person in charge of the mixer will determine the various sound qualities of each of the "signals" and then adjust them according to what sounds "right" to their ear. Mixer boards control both volume and tone, i.e. bass and treble outputs, and from the mixer the electronic signals go to their ultimate destination: the speakers.
If you are planning on spending the significant amount of money necessary to purchase a professional grade mixer, you owe it to yourself to speak with a qualified sound technician. They will be able to help you correctly determine your needs--including your growth potential--so that you can purchase a mixer that will work for you for the foreseeable future. In general, it is usually a good idea to purchase a little bit larger mixer than you currently need. This will allow you to be able to utilize the mixer in a wider variety of situations, and it will help ensure that you do not have to reinvest in a mixer a few years down the road.