The LD Systems HPA 1 is a versatile headphone amplifier with high output power, suitable for stage, studio, and home recording, and is 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 it is extremely well-equipped. 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 connection to 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 knobs, and a button switches from the stereo signal to the mono sum. For distortion-free playback and protection against feedback, a full-featured limiter is integrated. The LD Systems HPA 1 also features two-color LEDs that indicate, among other things, the limiter's response to peak levels and the battery status. Weighing just 165 grams, this headphone amplifier is exceptionally lightweight and can operate for up to 12 hours with a high-quality 9V battery.