Recently Roy and I set out to build set out to build a better headphone amplifier for our higher end Sennheiser headphones. A headphone amp simply boosts the power to the headphones a bit, this results in better sound on the bigger headphones. The design is built around a know design over at Diy Audio Projects. It is a Class A amplifier with a 12AU7 tube. We ended up puting a spin on the project and added a PCM2704 USB DAC (sound card). Sweet glowing tube action pictures are below.