Practical Devices Corporation is pleased to release the XM4 Portable Headphone Amplifier. We've worked very hard to provide you with what may be one of the most advanced, feature-packed, and best-sounding portable headphone amps on the market today. The XM4 is designed to be durable, flexible, easy to use, practical, and above all, sound great. Each unit is carefully manufactured, and the rigorously tested for performance, durability, and sound quality. And we are one of the few manufacturers who actually publish quantitative audio test results of our amps (click here.).

The XM4 delivers crystal-clean sound quality, packed with a combination of useful features not found on other amps. The robust anodized aluminum case and glossy laser-anodized faceplate combine to make the XM4 an striking sight to behold. The impressive engineering continues on the inside, where such things as military-precision resistors, oversized electrolytic and tantalum capacitors, and an ultra-low distortion FET amplifier chip contribute to the XM4's outstanding audio performance. Finally, the XM4's intelligent microprocessor control gives you an extraordinary set of features, including auto power-off, an internal battery charger (an optional Lithium-Ion system is available), variable crossfeed, and Bass Boost with bypass.