The mixer is like the heart of a pro audio setup, where all of the instruments signals and components come together. It's up to the mixer to tie them together and give you control over what the audience hears and how it sounds. And, of course, they're not just for live performances - a mixer is almost always what you'll find behind the glass at any recording studio. With that all said, mixers do come in a few varieties, including the selection of unpowered mixers you're browsing as you read this.
If you're new to pro audio, you might be wondering what the difference is between powered and unpowered mixers. That's simple enough to explain: a powered mixer has a built-in amplifier, and an unpowered mixer, like any of the models found in this section, does not. Why choose one or the other? Now there's a tougher question, and the answer is that it depends on the type of setup you like best. Unpowered mixers are the undisputed kings if your preference is toward versatility. Since you're not tied down to an internal amplifier, you're free to use any amp you want - or even to attach a crossover and use multiple amps at once. That's a big advantage of you're the sort of audio professional who likes to have total control and customizability every step of the way.
Another great thing about unpowered mixers is that, while examples like the Allen & Heath ZED-428 show that they can get pretty darn big, they can also be really tiny. If you want a portable rig, especially if you're going between locations that have amps available anyway, a compact unpowered mixer such as the Yamaha MG06X is a great toy to have. As with any other piece of audio equipment, the choice of unpowered mixer is ultimately down to your own needs and preferences. The variety of mixers here may be broad, but once you start narrowing them down based on what you're looking for, you can definitely expect a few leaders to surface. After that, all you have to do is choose between those - it's surprisingly easy once you get started.