The LD Systems HPA 1 is a versatile headphone amplifier with high output power, suitable for stage, studio, and home recording, making it the perfect connection solution for wired in-ear monitoring. This compact device features a robust, ergonomically shaped plastic housing with a soft-touch surface and a practical belt clip, and is equipped with a wide range of features. The HPA 1 includes locking XLR connectors for the symmetrical input of the stereo signal L/R, as well as a 3.5 mm stereo jack as an auxiliary input, which can be used in parallel for click or playback tracks. It is protected against excessive input levels for safe operation, and a hollow pin socket with a negative inner contact allows for the connection of a power adapter for fixed operation. A 3.5 mm stereo jack serves as the headphone and earphone output. Levels and balance can be adjusted with tactile rotary controls, and a button switches from stereo signal to mono sum. For distortion-free playback and protection against feedback, a full-fledged limiter is integrated. The LD Systems HPA 1 features dual-color LEDs that indicate, among other things, limiter activation during peak levels and battery status. Weighing in at just 165 grams, this headphone amplifier is exceptionally lightweight and can operate for up to 12 hours with a high-quality 9V battery.