the 1/4"-USB cable is an option, but i would warn you chances are you're going to get a terrible sound. That cables is going to have to do an A/D conversion, something that people spend thousands on interfaces to get done right. It is an option if you are not worried about the quality of the recorded material, but if you are going to, for instance, put the recorded material on CDs and distribute them, i would probably not jump on that 1/4" to USB cable. You're going to be much better off with a cheap little two channel interface, it should do the A/D conversion much better. Just pan the right and left the whole way to the right and left on the recorded track.
If i could steer you in another direction, you may be a prime candidate for a digial mixer of some sort. Lots of digital mixers are capible of multitracking all of their tracks to a computer using USB or Firewire connections, and also hold many many effects that you can use inside of the board. The only problem with this would be a.) the board won't be powered, so you would need power amps for your speakers and b.) digial boards are significantly more expensive than analog ones.
I ordered the Zoom R16, which is essentially a primitive digial board that records the information track by track to an SD card or onto a computer using build in USB compatibility. This is excellent for both studio and live situations, if you are using less than 16 tracks (you can hook two of them together), as it can multitrack all of the tracks you are recording, while adding effects, EQ, ext, and also play it back through a 1/4" left and right out. A great solution for lots of people if you ask me. BTW, the $400 is an amazing price for it.
Anyway, good luck on building live recording situations, i bet you wish you had all of the money by 10,000 person church has to record their live stuff

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