You also get a few master controls as well: a master volume allows you to attenuate or boost all four channels at once, while a master mute button will instantiate silence for every pair of headphones. Additionally, a master mono button will come in quite handy should you want to check the stereo phase of your mix through headphones.

To facilitate the connection of multiple QH4s—thereby achieving more than four headphone outputs by daisy-chaining units together—the QH4 features a stereo 3.5mm input jack and a stereo 3.5mm output jack. This high-power amplifier will work with headphones operating between 16 and 600 Ohms and can handle 564mW per channel. As such, is a suitable addition to your project studio, desktop workstation, or portable studio setup.
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 inputs—or one stereo 3.5mm auxiliary TRS input—and 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.