"The Objective2 (O2) is an open source headphone amplifier designed by NwAvGuy, with emphasis on benchmark performance and low cost. This item includes a preassembled and hand tested O2 circuit board, ready for use. You will also need an enclosure and AC adapter.
The O2 has created a stir in Head-Fi.org’s do-it-yourself community. After posting one too many "objective" (or possibly stubborn) comments, NwAvGuy found himself banned from the forums. He proceeded to design O2 for maximum benchmark performance to prove his points. It’s large and heavy, so hardly worth consideration as a portable amp, however, O2 so far lives up to its name.
For more information on the O2, please refer to NwAvGuy's O2 Details article."