Last one! The PreSonus HP4, with four headphone outputs and monitor level adjustment. There are minor scratches, but it works well. Body only. A universal adapter is available for an additional 500 yen. It can be used for various purposes such as band practice monitoring and streaming monitoring without sound quality degradation. A USB-powered monitor headphone amplifier with four headphone outputs. - Brand: PreSonus - Model Name: HP4 - Features: Monitor level adjustment, mono output - Connections: 4 x Headphone outputs - Power: USB powered - LED Indicators: Power LED, Monitor LED - Color: Blue Thank you for viewing.