Brief impression:

This small thing is simply amazing, compared with its predecessor ( only have ud100 for a few days before selling them)
UD110 still heats up like the UD100 but not as fast and goes as hot
UD110 is slightly more forgiving on bad recordings as compared with the UD100

As i only have the fiio E07k which utilize wolfson 8740, my impression will be compared to this unit.

UD110 has a larger sound stage compared with E07k
E07k gives a much warmer sound compared with UD110 ( which explains why UD110 has a bigger sound stage compared with fiio's)
Once again UD110 is still not as forgiving on bad recordings/source as E07k. Not sure how to explain this in detail but to keep it brief E07k gives a very musical sound where UD110 just doesnt gives that, should i say it is a very neutral sound?
Fiio's E07k definitely gave a "meatier" bass or should i say the quantity. I am not saying UD110 lost in term of bass but they give a different type of bass. A more detail bass and doesnt hit as hard and powerful as fiio's.

This is based on a 30min listening and could change when this unit burns in. I apologize in advance if there are typos, wrong usage of certain terms and grammar error lol