The D SERIES-HPA3 is a high efficiency 3.5 W power amplifier with one line input, an amplified output to drive a 4 or 8 ohm speaker and a separate headphone amplifier. The -HPA3 features a balanced line level input that may be connected unbalanced. The gain range will accommodate standard unbalanced levels as well as professional balanced levels. The amplified output levels are controlled by a front-panel volume control.