Hey guys, I have a question.
I want to buy the Boss rc 3 loop station and use it with guitar & microhone.
How do I connect my USB mic with the loop pedal? What cable/convertor/ do I need?
I do not think you can. The USB port on the Loop Station pedal is just meant for importing/exporting WAV files. I do not think it would work with a live feed from your microphone. Plus, the USB signal that the mic sends is a digital signal, one a computer can read- but the signal your pedal would work with through the guitar cable inputs are an analog signal- they are not compatible. If you used something like a USB to 1/4 cable, the signal quality would be extremely poor- but I doubt it would even work at all.

Your only real option is to get a mic with XLR pins, which is a typical microphone connector that sends an analog signal, and get an XLR to 1/4 cable. Run one input for your guitar, the other for the mic.