Art HeadAMP V – Five-Channel Headphone Mixer/Amplifier, 2007, made in China

Link: artproaudio | Owner's Manual

Specifications
Maximum Input Level +18dBV
Input Impedance 10k Ω
Maximum Gain 26dB/channel
Output Impedance 10 Ω
Signal To Noise Ratio > 90dB
Total Harmonic Distortion <.008%
IMD (SMPTE) <.008%
Maximum Output Power 300mW/channel
Dimensions 7.5×4.75×1.25 inches (190mm x 123mm x 30mm)
Weight 5lb (227g)
Power Requirements 12VDC