i think the only reason you would want to do this is to playback via the Ua-5, correct? but it seems like more work, and something to have to worry about while using it. For instance say what if you accidentally switched the switch over while using it for standalone. i would venture to guess it would stop working, and possibly could damage something in the machine. i personally wouldn't do it, kinda interesting, but not neccesary, just go the better route, and have oade mod it, get the warm or presence mod depending on what mics you have, its gonna be better overall.
also, if you didn't know once it is modded for standalone use, it can still be connected via usb. the only thing you can't do is playback. hope that helps. good luck.
matt