I got some PCBs fabricated and built a couple of Objective2 headphone amps with the default 2.5 and 6.5 gain levels. Only quality components from DigiKey have been used, the output capacitors have been increased from 2.2 uF to 3.3 uF for even better bass frequency response.

This amp is in the recommended enclosure, with silver front panel and black back panel from Head'n Hifi. The power connector is on the backside. Note that you'll need a 15VAC power adapter (see suggestions here).

There are no battery terminals in this amp, making it ready for installation of the ODAC (pdf).

For more info on the Objective2 headphone amp, see NwAvGuy's blog: http://nwavguy.blogspot.se/2011/08/o2-details.html

Technical specifications

• Frequency Response: +/-0.1 dB (20Hz-20kHz)
• THD 1 Khz 150 Ohms: 0.0016%
• IMD CCIF 15 Ohms: 0.001%
• IMD SMPTE: 0.002%
• Noise (ref 400 mV): -105 dB
• Max Output (33 Ohms): 613 mW
• Max Output (150 Ohms): 355 mW
• Max Output (600 Ohms): 88 mW
• Output Impedance: 0.54 ohms
• Crosstalk (15 ohms): -65 dB
• Channel Balance (50% volume): 0.6 dB
• Case Dimensions (mm): 108.50 x 80.00 x 29.50
• Case Dimensions (in): 4.27 x 3.15 x 1.16