The ultra-compact HM-4 4-Way Headphone Amplifier features a 1/4” stereo input and four 1/4" headphone outputs with individual level controls. Perfect for studios or even at home when up to four people want to listen together. 4-WAY HEADPHONE AMPLIFIER -Share a single stereo source with up to 4 pairs of headphones -Individual level control for each output -Powered via the included 12v AC adapter -"Built-Like-A-Tank" construction nánar