OK. I've been listening to a range of music on these now and here's what I have found.
The only way that I have found to get the potential out of these IEM's has been to use the supplied triple flange tips inserted deep. Very deep. Ear rapingly deep! Any less and not only does the bass suffer but also the upper mids take on an artificial quality. Especially the hanging tom drums.(thanks Wikipedia!
Get the deep seal and they sound pretty remarkable to me. Even slightly less insertion and they don't perform.
I have been chasing good quality sound most of my adult life. I am not certain how good at analysing sound I am but here goes.
Straight out of the headphone jack of an iPhone 4S they sound very good but if I was being picky I would say that the bass ( lots of it) is rather unfocused and "plumy". The good news is that the rest of the frequencies are very nicely balanced with the large amount of bass. ( Unlike the IE8's!). The soundstage is good. Nice and out of the head. Just occasionally I am aware that the sounds are coming from tiny drivers within my ears but on the main not.
Plug a LOD and amp into the iPhone and things get even better. The pluminess disappears and there is more air and separation around the instruments. I was not aware of the location of the drivers at all.
All in all. If only these 'phones worked with shallow insertion they would be amazing. As things stand the sound is amazing but only if you can tolerate the deep, deep insertion. It remains to be seen if I can. I was pretty relieved to take them out just now!