1. Small and Compact. 2. Easy-to-Connect Plug-n-Play USB Interface. 3. Digital Analog Output This product supports both optical and coaxial types of digital outputs along with analog 5.1 channel outputs.4. 3 Volume Controls 3 Volume controls provide independent level adjustments for the Front, Rear, and Center/Subwoofer output channels. (For digital output, the volume can be controlled by a volume control on a speaker.). 5. Amplifier included A built-in amplifier provides full sound and ease of use.