Interesting you say that Bob. I've been struggling a little with the U6 as well. Obviously I couldn't test any because of my location. I chose the U6 because I figured it would be nicely balanced, and because I was concerned with the Adel module, that having it open would compromise the bass. The bass is actually perfect on the U6 - wouldn't change a thing. Where I'm struggling is the lower mids in relation to the upper mids. They seem to be very, very flat, and there is no upper mid/lower treble peak. Some may think this is a good thing - but I'm really regretting not going all out and getting the U10 now.
I gave them to a friend (who has a very good ear - and we often have similar thoughts). He's involved in the design of IEMs (sorry can't say much more than that). He described the mid-range as "lifeless". I wouldn't go that far - it s really detailed,and for male vocals and rock music it is pretty amazing. But I would say that it just doesn't suit my preferences. Interestingly, I used EQ and gave it a simple bump at 6 kHz and 8 kHz, and it's a different earphone.
I've included a graph - raw data only - showing measurement of the U6 and comparative measurement of my q-Jays. The graph is just for comparison. It is uncalibrated and uncompensated - but I'm showing it so you can see the frequency deviation vs the q-Jays
Without EQ - I prefer the Jays.
![](https://www.head-fi.org/attachments/1480927/)