Pros: neutral and smooth sound, fair power to drive cans, good dac out
Cons: poor quality of included power cable, small vibration
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.
The tube might get really hot, 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.
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.