Headphones rarely have much bass, and mobile devices rarely put out much power to those headphones anyway. If you're looking for a little more oomph from your mobile audio, Make shows off how to do just that.
The build here is fairly complicated, but you'll be able to get all your parts easily. Once you're set, you'll need to some soldering and glueing to get your circuit working. From there, you'll just need to get the input/output box working and install some knobs. It's by no means a beginner's project, but Make guides you through the steps very clearly, and the end result is better-sounding music.
Bass Bump Headphone Amp [Make]