I told this story in the new member introductions, but think it might be worth posting here as a cautionary tale. I very nearly returned my Nexus 7 to Asus for a replacement. I made the false assumption that if you could hear music coming out of the internal speakers, you would hear music coming out of your headphones, external speakers or your car stereo when you plugged them in. I spent a frustrating week trying every set of ear buds, headphones and powered speakers I could find. I made sure the plug was fully inserted. Nothing worked. My last ditch effort came from Asus technical support. After several go arounds they suggest I check the mute or speaker volume. I maintained this made no sense as I could hear the music coming out before I plugged in my headphones. I was chagrined when I saw my volume was next to zero. Turned it up, I could hear just fine.
It was embarrassment mixed with pleasure. Not the first time I have felt this way. So perhaps you can learn from this and save yourself a lot of aggravation. Don't overlook the obvious and don't be afraid to ask for help.