Fully discrete bass and gain circuit, with new toggle switches for easier use and operate. Can work while charging, 1400mAH built-in battery with more than 12hrs of battery life. The aluminum-alloy body  increases shielding from EM interference. The Power amplifier AD8397 serves as a current amplifier, with great control of low frequencies and smooth drive.Preamplifier OPA1642 serves as the voltage amplifier, with great layering and medium and high-frequency extension.

Power Supply: MINI USB Port
Maximum output power: 270mW (32 Ohm THD <1% )  450mW (16 Ohm THD< 1%)
Frequency response: 20Hz~20KHz
SNR: >108dB
THD+N: 0.004%(1KHz)
Charging time: <4Hrs 
Operating time: >12Hrs
Drivability: 16~150 OHM
Power Supply: MINI USB Port
Maximum output power: 270mW (32 Ohm THD <1% ) 450mW (16 Ohm THD< 1%)
Frequency response: 20Hz~20KHz
SNR: >108dB
THD+N: 0.004%(1KHz)
Charging time: <4Hrs
Operating time: >12Hrs
Drivability: 16~150 OHM
Features:
Fully discrete bass and gain circuit design.
New toggle switches and more reliable and easier to read and operate.
Can work while charging, 1400mAH built-in battery ensure more than 12hrs of battery life.
All aluminum-alloy body and chassis increases metal texture and increases shielding from EM interference.
Power amplifier AD8397 serves as the current amplifier, with great control of low frequencies and smooth drive.
Preamplifier OPA1642 serves as the voltage amplifier, with great layering and medium and high-frequency extension. XtremPro Portable Headphone Amplifier Aluminum body w/ L-Shaped Plugs – Black (M1)