Now that scientists have definitively proved that two heads are better than one, just think of the awesome power you can harness with the HA43 Pro headphone amp!This four-channel stereo headphone monitoring device is a no-brainer for any recording studio, listening room, or monitoring station. Each output boasts a whopping 20 dB of clean channel gain with a full frequency response of 20 Hz to 20 kHz to ensure faithful sound reproduction. Stereo 1/4″ and Dual RCA Inputs Slider Volume controls 20 Hz-20kHz frequency response Lots of output level AC adapter included Input Impedance: 100K Ohms unbalanced Max Input Level: +14 dBV Input Connectors: TRS Stereo 1/4″ phone, Dual RCA Outputs: 4 TRS Stereo 1/4″, 4 TRS Stereo 1/8″ (3.5mm) Output Impedance: 51 Ohms each output Max Gain: 20 dB/Channel S/N Ratio: > 90 dB THD: < .008% IMD (SMPTE): < .008% Power: 12 VDC (Rolls Model PS27) Weight: 1 lb (.45Kg) Size (W x H x D): 4.15 x 3.45 x 1.16 inches (10.5 x 8.75 x 2.9 cm)