Thanks a lot for your reply

I see you own also the ER4XR. How would you compare the IE600's to the ER4XR ? Which do you like more overall and why?
That's almost a apples and oranges comparison. Both are round and come from a tre... But...
Jokes aside here.
Aside from frequency response, , one is neutral and the other is U-shaped, the biggest difference is soundstage. The IE600 has better imaging and much much better soundstage. It can even soundstage outside if your head, - and that is impressive. Also it's bass and sub-bass response is very deep end expended... And that's where the trouble starts for the IE600. - sometimes.
On tracks that have a deep background subbass, the IE600 gets in trouble because this subbas will dominate the music to the point where it even can ruin things.
A exsample would be London Grammer - Californian Soil, this track mas great soundstage that plays go the IE600 strength with it's slightly elevated treble, but the subbass is just there constantly, and that starts to be tiresome. As this is a track with a soundstage "build in" it sounds just right, not to wide, not to bassy, on the ER4XR...
But this is only a problem when listening at 90db... At 80db spl everything sounds very neutral ( even if it isn't when looking at a graph)
Now the IE600 on the other hand.. if we take Five finger Death punch with the song Afterlife ... Now this is a sound that has bass, but not alot of subbass, some guitar, fats pace, and where you want to feel the music. The IE600 is just mind blowing with this track, where the ER4XR is borring, narrow, with little impact ( compared ).
Isolation wise the ER4XR wins hads down.
Comfort IE600....
Overall, when I'm listening to music, and don't need the isolation, I highly prefer the IE600. Its soundstage is wide ( wider then my HD650 ), so it is the IEM I take when traveling to hotels and so on. But it's best to listen to it when there is not to much noise around.
The ER4XR is the one I use when I need to cut out the world. I can listen at low low volume, I get great detail, and it's just "me and the music"
If I had to pick only one, it would be the IE600.
Hope that paints a picture...