I've received a couple of PM's to get more impressions of the U10, so I thought I'd share some of those thoughts here:
The housings are really tiny. Frankly I'm surprised how small and I had to get my reading glasses out to read the model and serial number engraved in it to be sure it was the 10 driver model! The nozzle is pretty small too considering it has 4 bores. I don't see fit being an issue for the average person. Reversed Comply tips work pretty well.
From what I can tell, the Adel modules makes it sound different from a normal multi-ba. It sounds more organic, more dynamic driver like. There is a sense of air all throughout the frequency response, so when I speak of the U10 having an airy presentation, it's not about how it presents treble.
Also regarding the Adel feature, I've definitely noticed that I don't pressure build up over long listening periods. But the whole thing about listening at lower levels seems silly. The U10 has different sensitivity, so the volume clicks on my daps may be more or less depending on that. Otherwise I still listen at the same volumes, depending on mood and song.
Bass is a pretty prominent feature. It has a rise into deep bass and extends to about 24hz before rolling off. Bass is full, rich and plentiful. Lower mids are also full and forward as well. This works really well for male vocals and I'd say this is their specialty. Upper mids have dip, so female vocals don't have the same energy male vocals carry. Treble picks back up after the laid back upper mid but is never harsh or piercing. It's easy going treble but provides good sparkle.
The airiness previously mentioned lends itself towards a very open ended sound. While staging doesn't come across as grand or huge, it definitely doesn't sound boxed in and head confined. It's a natural and easy going openness. Again this is more reminiscent of how dynamic drivers present the musical package than a multi-ba, so it doesn't have the separation like a typical high end multi-ba design but again presents things more organically or holistically.
So the overall presentation isn't really close to neutral, which is what I had thought when making the purchase. It's a male vocal oriented monitor with plentiful bass, and an airy, open ended presentation.