This PreSonus HP4 headphone amplifier is a great choice for audio enthusiasts. However, it does not come with a power supply. Also, please note that the rubber feet are missing. Despite these minor issues, it still offers reliable four-channel amplification for your audio needs.

To use this PreSonus HP4 headphone amplifier, first, you'll need to connect your own power supply as it's not included. Once powered, you can plug your headphones into the available channels. When using, make sure to place it on a flat surface, even without the rubber feet. For maintenance, keep it in a dry and clean environment. Avoid exposing it to extreme temperatures or moisture. Regularly check the connections to ensure a stable audio output.