Here's a little DIY headphone amp I built with the help of my buddy Dan. It's based on the design of a grado amp but with two batteries for extra niceness. The case is made of solid routed Mahogany treated with a bunch of tung oil to keep the clean look. I left a lot of space in there in case I ever want to put in a DAC. I also put a knob on the front to clean it up so it doesn't look so goofy.