Warranty It is in Hifigo 1 year warranty. Every Dx220 max has an unique number since there is only 999pcs. It is included in the box of the package together with warranty card. Meanwhile, there is an SN number outside the box. Pls keep these original box and warranty card for HIFIGO warranty. Features of iBasso DX220 Max:- >Dual ES9028 Pro DAC chips. >Five Batteries, one for DAC and CPU, four to form a high voltage battery pack for the analog stage. >Premium Components. >CNC Stainless Steel Body. >Multiple Headphone Output Ports. >4.4mm Balanced Line-out Port. >SPDIF Output. >Analog Volume Control. Five Batteries Setup:- The iBasso DX220 Max features five batteries. While one is used to power up the CPU and DAC, the remaining four batteries form a high voltage battery pack for the analog stage. Usually in other systems single battery handles the DAC, CPU, and Amplification circuit, this introduces noise in the final output that is difficult for cleaning in the post. In DX220 Max the separate current for amplification portion rectifies this and provides the best sound output with ultimate clarity, completely free from any kind of background noise. These also feature separate charging via DC-in and USB Type-C ports. Analog Volume Control:- The iBasso DX220 Max features analog volume control. Usually, Desktop DAC/AMPs are equipped with analog volume controls, this enables precise volume management on the device. Premium Build with Multiple Output Ports:- The iBasso DX220 Max has a rich and heavy built with CNC Stainless steel body. It features multiple output ports including a 3.5mm unbalanced port, 4.4mm balanced port, 4.4mm line out port, SPDIF output port. The maximum output from the balanced port is up to 8.8Vrms, more than enough to power the most power demanding headphones with ease.