Samson QH4 4-Channel Headphone AmplifierFEATURES Split one audio source into four discrete channels with the QH4 Headphone Amplifier from Samson. Simply route audio into the device through two 1 4" balanced inputsor one stereo 3. 5mm auxiliary TRS inputand then, through its multiple stereo 1 4" jacks, you can plug in up to four pairs of headphones, all the while manipulating the individual volume of each pair with four on board knobs. You also get a few master controls as well: a master