The DX220 Max is a transportable solution to your audio needs. It offers extremely high performance to enhance what you enjoy so much, music! It is powerful, very transparent and engineered to work with most any listening device. A great partner with the DX220 . 1. The frame is stainless. 2. Dual ES9028pro chips are used with extremely high quality components surrounding them. 3. It has batteries being used. A battery for the DAC and CPU, the rest (4pcs) of the batteries form a high voltage battery pack for analog stage. 4. Analog volume control. 5. The price will be around 2,000USD.