The USB connector on the Sender transmits USB audio from your computer OR you can plug any input into the audio connector on the other end (an iPod, stereo, etc.). The Receiver part is powered by a USB power supply or charger and sends out analog audio. Just keep in mind the W3 will work anywhere you want to replace an RCA cable or 1/8" mini-jack cable with wireless! If i purchase multiple W3 sets will they interfere with each other when used in the same setup? Up to 8 W3 sender receiver pairs will play well together as long as you keep a minimum of 6 inches between each unit.