The Objective2 (O2) is an open source headset amplifier created by NwAvGuy, with emphasis on benchmark performance and low cost. This product includes a completely put together and hand checked O2 amplifier, all set for use. You will just require an Air Conditioning adapter appropriate for your region.
The O2 has developed a stir in Head-Fi. org's do-it-yourself neighborhood. After being banned from Head-Fi for heated discussion, he proceeded to develop O2 for maximum benchmark performance to show his points. It's big and heavy, so barely worth factor to consider as a portable amp, however, O2 measures up to its name.
Alps Dual Analog Potentiometer, 3.5 mm Input and Output Jacks, Dual Gain Switch (2.5 x and 6.5 x), Opamps: JRC NJM2068D, 2x JRC NJM4556AD, Air Conditioning Jack - Rechargeable 9V NiMH Batteries
Frequency Response: +0.01, -0.01 dB (20Hz-20kHz)
Gain: 2.5x and 6.5x
Output Impedance: 0.5 ohm
Volume Potentiometer Taper: 15A or 3B
Case Dimensions: 108.50 x 80.00 29.50 x mm (excludes knobs/buttons), Weight: 11 oz, with batteries