Hello, I find a way to connect an external sound card pre mk2 avid mobile, thanks to a female connect on a nokia phone battery (3.7V) USB cable, you can also take a 4.5v battery or several batteries 1.5v or 1.2v rechargeable connect to a uSB port for the black female body and the red +5 v everything, it's easy

4 batteries 1.2v or 4.8v should be the best solution, I took what I had on hand is just to try, this is not the final cut. it is a lower cost solution that works very well, and although cheaper than a mixer,   to make its "mobile first" first truly mobile thanks card has a battery via the USB socket.

I did not even try to connect the mobile pre mk2 on my gh2, because I do not know exactly the reliability and sensitivity of the input level jack2.5mm. But the microphone prodipe st1 out very well in the headphone sound card and line output

This system must work with other external sound card usb