I have uploaded two screen capture from Taobao for your reference:
The first picture are the differences of XS-03 to XS-02, such as the use of 4493 instead of 4490, use of class A for amplification, 3.5 balance output, the additional USBDAC function and a larger battery. The second explains that of XS-02 and XS-01, the XS-02 uses dual 4490 while XS-01 mono 4490.
I think XS-03 is an upgrade of XS-02, it supports more file format, has more functions and provides balanced output. XS-02 does not provide any balanced output. Only XS-01 has the option for swapping the op-amps according to the pictures I saw on Taobao.
Hope this helps.


The first picture are the differences of XS-03 to XS-02, such as the use of 4493 instead of 4490, use of class A for amplification, 3.5 balance output, the additional USBDAC function and a larger battery. The second explains that of XS-02 and XS-01, the XS-02 uses dual 4490 while XS-01 mono 4490.
I think XS-03 is an upgrade of XS-02, it supports more file format, has more functions and provides balanced output. XS-02 does not provide any balanced output. Only XS-01 has the option for swapping the op-amps according to the pictures I saw on Taobao.
Hope this helps.