Hi, I have a pair of LogiTech speakers. It has only a USB to plug in my Macbook. No line in, no 3.5mm jack nor RCA jack. It is a decent pair of speakers and I would like to convert it to bluetooth capable. What I need is a Bluetooth receiver, I guess. A receiver that can output audio via USB to the speakers and gets power from the USB on the speakers, battery or external power supply. I don't seem to be able to find a device like that after googling. Does a device like this exist? If so, what is it called?