In this repo you will find a headphone amplifier mainly developed for in-ear monitoring.
The amplifier is designed to be driven with symmetrical audio signals connected via XLR. It converts the symmetrical signals (Left and Right for stereo or only Right for mono, switchable) to an unsymmetrical signal. This signal is further amplified to drive headphones or in-ears. Beside the complete eagle schematics and board files, the repo contains a 3D printable casing. It is designed so that it can be attached to your belt. The amplifier is powered by 2-AA battery cells. These should last easily 50 hours, so enough time for some band sessions or concerts.
If you are interested in building one or have any questions feel free to contact me.