Pros: neutral and smooth sound, fair power to drive various cans to IEs, good dac out
Cons: poor quality of included power cable, small vibration, some noise on volume
I use it with optical input and it is fantastic. The sound is quite neutral and can match with any sort of headphones and IEs. Through the USB input, the sound is less dynamic and microdetail is a bit inferior.
The tube get really hot if you turn it on for days, but you can take it away if you don't need it.
Included power cable didn't work at all. I got one with $3 at local store and it works fine.
After a year of use, the volume makes horrible noise as its rotating. Using some grease sorted out the problem.
Not recommended to plug in and out heavily with bulky plugs, such as Furutech.
When I touched it while it is working I felt very small vibration. I tried to get rid of it but I could not figure out what is the cause of that vibration. However I don't think it ruins the sound quality as far as I could perceive.