Thank you very much for the tip. It is a great song not only for testing but also for listening. Very enjoyable.
I first used the single BA driver Brainwavz B100 ($50) followed by the **** UES ($25). The B100 sounded a bit cooler overall, particularly in the bass department. Here, the UES's additional dynamic driver added some temperature. I then used the much more expensive UE900S ($399; on sale $179)) which really excel in resolution with their 4 BA drivers. But the "wow effect" came when I plugged the UES in again. Hayley's voice was almost on par with the UE900S - with some sibilance in the UES. Hayley sounded very natural with both iems. The biggest difference was again in the bass, which was much more controlled in the UE900S - you expect this for the money. But wow did the UES fare well in comparison. I speculate that's why the names of the two earphones are so similar, each containing UE...S.
All three iems have a coherent sound; it is no surprise for the B100 with its single driver or the expensive UE900S simply for their price, but I am impressed how well **** tuned their rather unspectacular looking UES. For people who are drooling over the forthcoming KZ models, have a look here. You may do better without the hype. First indication: the new two-driver KZ ED15 bass cannon is no competition for the UES IMO.
I have to add that I had to overcome some sealing problems with the UES. The included tips are too small for my ears, I used my standard third-party ones with a relatively narrow bore. They always add a tinge of boom to the bass for the benefit of getting an overall fuller image. And I have to push them right down to my tonsils.