Unless I've missed something, a midi to usb cable can't record sound without a microphone on the other end. but heres the thing, weather my mic (mxl 990) is plugged in or not, my computer reads a constant max input level from just the usb and if you record this you get a sound almost similar to feedback, but much quieter and softer. the exact same setup works perfectly well on the laptop and records beautifully. then you switch the usb to the desktop without even moving anything else and all you get is this constant unflinching max input level, EVEN WHEN THE DAMN THING ISN'T PLUGGED IN!!!! I've tried different audio drivers, I've tried finding mxl drivers of which there are none because it is not the usb version but the proper version. it doesn't record any other sound, doesn't do anything apart from this extremely quiet high pitched buzz. Yes, the phantom power is set up correctly and no, it isn't actually feedback, its something to do with the computer but theres nothing else i know how to try.... help!