I am working on exactly the same thing. From what I can tell, the usb mic is powered by +5v DC supplied by the usb cable, whereas a conventional condenser mic would typically be powered by +48v Phantom power (which is technically DC as well). The problem with this is that the +48v and the +5v are supplied in different ways, and the phantom power (needed to boost the signal to a point that it can be heard by the mixing board or amplifier) is too strong for the components of the usb mic. I am currently looking into the possibility of replacing the circuit board but I am not very optimistic. I’m sure it can be done but I’m not sure if it’s worth this much time and effort.