Fostex HP-A4BL headphone amplifier with balanced and unbalanced connections, featuring filter selection and gain adjustment. - Brand: Fostex - Model Name: HP-A4BL - Connection Type: Balanced / Unbalanced - Features: Filter Selection / Gain Adjustment / Output Selection - Output Terminals: Headphone Jack (Balanced / Unbalanced) Thank you for viewing. Includes only the main unit and power cord. Please note that the box and instruction manual are not included. *I have been using this for several years, and there is a symptom where noise appears after turning on the power. I am not sure if this symptom only occurs in my environment, but I would appreciate it if you could purchase it only if you understand this.