I travel with just smartphone. It works as a camera. It works a GPS. It works as reading device. It works as a way to communicate with people home. It can work as a lifeline, if needs be.
So yeah, I would skip everything except smartphone and a headphones. It depends on what smartphone it is, though - 64 GB one, and a few bucks of Dropbox subscription could carry you through much cheaper and safer.
Though, if you carry that much electronics, get a powerbank and a something like this: 1 it's pretty annoying when there's just one outlet.