Paid $59 for this on eBay from the manufacturer but after about 3 hours of use decided my headphones really don't need more amplification. It can be powered by the included A/C adapter/charger or two rechargeable AA batteries. Since I only used the A/C adapter, no batteries are included. Has a lifetime warranty which is transferable to the buyer. This unit has received a lot of positive reviews on Head-Fi and other audiophile forums. Here are the specs:
- Frequency Response from 5 Hz to 40 KHz
- Signal to Noise Ratio (SNR) of 100dB
- Variable gain from 0 to 610% (Amp numbers 5000 and below)
- Independent left and right channel gain adjustment screws (Amp numbers 5000 and above)
- Enhanced EMI shielding case (Amp numbers 8000 and above)
- 100+ Hours of battery life
- Dimensions are 2.2" x 2.2" x 1.1" thick
I'm asking $35 shipped to anywhere in the US. International shipping is extra. I can accept any payment method other than US poker site transfers -- I wil not accept payment on Merge, Cake, etc.