After spending couple days with the u4s, i must admit that i love them. This is first time i dont miss my beloved Monarch 2. I dont even look a the box where they rest in peace
I didnt even have this feeling after spending some time with u12t.
For me they are complex- fantastic bass, clean and inoffensive midrange and great extended, smooth treble. The soundstage is very spacious and coherent, all blends together, nothing falls apart. Even the imaging is almost on par with the Monarch when checking with tracks like "Bubbles" or "Letter" from Yosi Horikawa. They are very close in this department but the u4s have this specific physicality behind the notes that i havent heard from any iem before. They push air almost like full sized open back planars (even more than the Sundaras which sound thinner in comparison).
A great allrounder.
Also the form factor and comfort are top notch.