When I plug a bass, guitar, synthesizer, or basically anything other than a mike to inputs 1 & 2, I get a great input level without peaking as expected sense those channels are made for mics or instruments. When I plug anything that isn't a mic into channels 3 through 8 I can't get a descent input or output level without cranking the channels gain knobs all the way up and they still don't compare to channels 1 & 2. I am wondering if I need to get some kind of seperate pre-amp even though the firepod claims to be a pre-amp. I need to figure this out because I find myself recording more than just one bass and guitar which means I need to use more than just channels 1 & 2 for instruments.

That's because of the difference in impedance between mic, line, and instrument.
Channels 1 & 2 on the Firepod are able to take inputs from instruments, while 3-8 are not pre-equipped to do so. You will need a direct box (DI Box) to plug a bass/guitar/keyboard/etc.. into channels 3-8.

I have looked at several direct boxes and I was wondering what the benefits to having an active direct boxed over a passive one is. I know that difference between active and passive, but I just don't know how exactly that helps in this situation.

Hi,

I use a firepod - 1 & 2 are designed for instruments such as bass or electric guitar that don't have preamps (by contrast to an electro acoustic guitar, for example). If you read the manual you would learn that you should NEVER plug anything active into 1 or 2....

So plug your bass or electric guitar straight into 1 & 2 but not if you are using pedals/DIs etc in the chain.....

Inputs 3-8 are designed to take active stuff such as electro acoustic guitars, keyboards etc........