Features: No Power Required, Plug and Use:It can be used just by connecting it to the device interfaces. No external power supply is required, and the operation is simple. High/Low gain switcher for optimal performances of the headphones. TheXLR input connection features a locking mechanism to prevent accidental cable disconnection. Simply press the tab next to the bottom mount connector to release the cable at the end. Standard 3.5mm Headphone Output Port:The metal 3.5MM headphone output interfaces can easily connect regular earplugs or professional monitoring headphones, giving you a clear music experience. Usage: 1.Please keep the volumes control ofthe headset and plaver to a minimum before connecting. Connect the input plug of the headset volumes controller to the output of the player. 3.Connect the headphone plug to the output socket of the headset volumes controller. (if you use a headset other than a 3.5mm stereo mini plug,be sure to configure the appropriate adapter.) 4.Adiust the volumes ofthe player and headset volumes controller to the appropriate setting tolisten to the appropriate volumes. Specifications: Material:Metal Color:Black Size:Approx.91x30x25mm/3.58x1.18x0.98in XLRto 3.5mm Interfaces Note: Please allow 1-2cm errors due to manual measurement,please make sure that you do not mind before you order. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Package includes: 1x3.5mm Headphone Amplifier 1xXLAConnecor 1xManual