LD Sytems HPA 4 - a compact and powerful headphone amplifier The LDHPA4 has small dimensions, can handle up to 4 headphones and has an output power with no equal in its class. That means high volume with no distortion. With these features the LDHPA4 is an essential tool for every project- and home studio. Product type Headphone Amp: Inputs 2 Input connectors 6.3 mm TRS , RCA Input impedance 1 k Ohm(s) Outputs 2 Output connectors 6.3 mm jack Power output 4 x 100 mW Minimum connected impedance 10 Ohm(s) Frequency response 20 - 20.000 Hz Controls 4 x headphone volume , Mono/stereo switch Indicators Power Operating voltage External Power Supply Operating voltage 24 V DC Cabinet material metal Cabinet surface painted Width 94 mm Height 48 mm Depth 82 mm Weight 0,27 kg Accessories (included) power supply