Cupid - I am going to assume from your last reply that you currently have a basic sound card (like a Sound Blaster product) that will record one stereo track (or two mono tracks together) at a time.
All the digital connections (ADAT, S/PDIF etc.) in the MOTU are for interfacing with digital equipment ONLY. If you want to "plug 8 - 12 mics into the computer" there are two ways to do this:
1) Buy a mixer. If you are recording a band live, using a bunch of mics on drums, guitars, etc you run all your mics into the mixer, run the stereo master output into your current sound card, end of story. The big limitation in this case is your mix is also done live - i.e. if it's not perfect, there is no way to change your relative instrument levels later.
2) Buy a device that records multiple ANALOG INPUT sources at one time. I believe the MOTU records up to 8 tracks at one time, and can play back as many as your computer can handle (they all need to be assigned to one of 8 different OUTPUTS the Motu can handle at one time). If you go this route you will want to buy a mixer anyways, as a mixer is generally needed to boost the signal level from mic level to line level. Plus a mixer is VERY useful for EQ, mixing effects, stereo panning, etc. etc. etc.
A real world example - I have
a Gadget Labs Wave 824 card, a similar product to the MOTU with 8 analog inputs and outputs. I use
an Alesis Studio 32 mixer. Usually when my band records a song, we start by using 2 inputs for drums (an electronic kit, stereo left/right outputs), one for bass (either direct through the mixer or a mic), one for guitar, and a fifth input for a "scratch" vocal track that is almost always re-dubed later. then we add more tracks as needed. If I were using a real drum kit I would need at least 6 mics on the drum kit, and I would either use an input channel for each plus one each for bass and guitar (=8, and add the vocal later) or I would do a live mix of the drum kit down to 1 stereo left/right track.
Hope this counts as english....