My God, Wack, I hardly know where to start. Here's a snippet I wrote to a guy who was asking about PA's:
"Every PA is a combination of a mixer (which is a bunch of preamps with controls that sends however many inputs you have to a smaller number of line outs. It usually has EQ on each channel, and adjustable reverb for each channel), a power amp (which raises the line level to something that can drive a speaker), and one or more speakers (usually in at least 2 identical arrays). Each speaker array is likely to contain dedicated speakers for lower frequencies (woofers), higher frequencies (tweeters/horns), and midrange frequencies (drivers). In larger systems, a single subwoofer is added to handle really low frequencies.
The differences are in quality/price (like everything else in the world), power, number of channels, and what boxes the components are in. A component system keeps it all separate. You use an unpowered mixer (most basic mixers are unpowered), to one or more separate power amps, to passive speakers (ones that don't have a built in power amp).
Another version is an unpowered mixer to powered speakers, such as Eons. This is very portable and simple. The downside is you can't use those power amps to drive anything but those powered speakers. The upside is it's simple, and usually, the amps are well matched to the speakers, because they were built to work together.
The third version uses a PA head or powered mixer to drive unpowered (passive) speakers, It's the same deal, but the power amp is built into the mixer instead of into the speakers.
No matter which version you use, the mixer, the power amp, and the speakers have to match in impedence and in power output/input.
So which is better? No simple answer, dude. It depends on your preferences and your needs. One thing to remember- The more components you have in one box, the more convenient and portable it is, the less versatile and flexible it is, and the more stuff that's out of action if one part of it breaks."
For your purposes, a powered mixer makes no sense. Some really good powered mixers have line outs, but on many, there are only main outs for driving speakers. You can't use those outputs into a digital recorder. The signal that drives a speaker is not line level, and you don't ever want to plug a speaker out into a line in. That, as Moresound says, is very bad juju.
Be advised- the purpose of a mixer is just that- to "mix" a number of inputs into a smaller number of outputs, with multiple routing options. You are trying to get more inputs, but only a few mixers will give you separate line outs on each channel. The groups of outputs are called "buses", so a 16X4 mixer has 16 inputs, and only 4 outputs. If something is mixed together on input, you can't separate it later. So- The first thing to do is find out how many tracks your recorder can simultaneously record. You can't change that. In your case, I think that's 8.
So what you really need is not a mixer. What you need is at least 6 channels of mic preamp s with 6 lines out. For cheap (as they go), consider Behringer ADA8000:
http://www.8thstreet.com/product.asp?ProductCode=20720&Category=Audio_Interfaces
So here's what you do. First, get a short optical toslink cable (1 foot will do). Connect the ADAT out to the ADAT in on the 8000. Now you have an 8 channel mic preamp. Then you need a bunch of XLR to TRS 1/4" cables (whether you use a preamp, a mixer, or whatever, you're going to need a bunch of cables for all those inputs) and plug those line outs into the line ins on your channels 3-8. All I can tell you is that the preamps on the Behringer are at least as good as the preamps on most mixers,and in many cases better. Now you have your 8 channels in. Best of luck.-Richie