A:AnswerIf I understood your Q correctly:
The USB delivers the POWER needed to drive the speakers. The audio comes from the audio plug on your PC or laptop.
At least that's how it worked out for me...I was also stumped for a while trying to figure the configuration out - but very happy at the end :-)
A:AnswerNo. I was amazed with the sound quality forbadncheap as they are it's a great product. I use it to stream Netflix off of my laptop and have a louder setup.
A:AnswerYou can not plug a headphone jack into these speakers ... there is no audio output .. to use headphones you will have to unplug these speakers form your computer.