I am using my SP3 in the classroom for teaching. In 2 separate rooms now I have hooked my SP3 up to a provided audio jack and not had sound come out of the classroom speakers. My SP3 continues playing audio through its built in speakers just fine. I thought it might be a problem with the jack and so in both cases I put the jack into my iPhone. It played audio through the system just fine. Is there something special I need to do to have the SP3 send out audio via the jack port? I ordered one of these (http://www.amazon.com/gp/product/B004SP0WAQ/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1) in case that was the problem. It hasn't come in yet for testing.