I have both Schiit Vali2 and XDuoo MT-602. Not a scientific review but I am sure people would wondering how these two compares.
* 2 gain stages. Easier to match IEMs
* larger, easiest to find, cheaper tube. No need to match it.
* warmer, more realistic, wider sound stage
* better performance as a preamp
* glowing orange light is brighter, prettier
* no pop sound when turns on or off
* much better circuit design
* much better...