Since the utws3 becomes your DAC/amp the difference you hear has far more to do with your source, when wired, than your iems. I used then with the UM Mest and was very impressed. Coming from an ibasso dx220 I could tell that staging was not quite as expansive or 3 dimensional but it was a small difference. They are also a little more v shaped but for me that makes them more fun rather than being an issue.Does sound quality suffer at all when you use your iems with the UTWS3?
For the audiophile world,I think these are a fantastic option. I would take these (coupled with my iems) over Sony's wm series any day. They are in line with Fiio's practice of offering high quality audio for a very fair price.