The S0 In-Ear Monitor Belt-Pack is ideal for personal monitoring applications. Made for musicians who tend to be in fixed positions on-stage, like drummers and keyboard players, the S0 is a simple solution to hearing your own performance and is incredibly easy to use. A quality volume control allows users to set precise volume levels every time. The XLR input features a intuitive locking mechanism and there is also a 3.5mm jack headphones connector. Note:It is just a level control. You'll still need a headphone amp to drive your monitors.You need to feed it with a headphone amplifier, could be the one on your mixer, or outboard. SPECIFICATIONS Input : XLR, stereo pin 1: GND, 2: L, 3: R) Output : 3.5 mm jack, stereo Maximum power : 100 mW Headphone impedance : 32-600 Ohm Dimensions : 30 x 30 x 90 mm Power : Passive Weight : 80g