The make up of the API Audio 8200 isn't too hard to figure out as it's basically got a number of features you'd get from a traditional analog mixer. Each of the eight channels has the same make up, with parameters for pan, level, two knobs for aux sends, and buttons for mute, INS, and AFL solo. That's what you'll find on each of the eight channels, so it should be pretty self explanatory if you're familiar with the general make up of mixers. The manual has everything you'd need to know about this, so definitely check it out if you're at all confused.
The sound of the API Audio 8200 is through and through, outstanding. If you'd like something to warm up your inside the box sounds a bit, the 8200 is ideal and is perfect for this application. It adds fullness and depth to your tone, with a sounds that isn't possible without using real analog circuitry. Of course it's made by API, so I wouldn't expect anything less from them. Basically you're getting the sound of a big console without all the hassles of it.
The API Audio 8200 is the perfect line mixer to add to your home or professional studio if you don't have a console. It's much more than just a summing box, as it's got the traditional mixer parameters to give you more control as well. It's not the cheapest out there, but then again you're getting eight channels of API gear. If you have a home studio and are looking for a little analog mixer to team up with your DAW and that will take up the least amount of space possible, the 8200 is for you.