I bought the IE 100 Pro for casual listening and music production, and am overall very happy with them.
They replace a pair of beyerdynamic DTX-101iE and DTX-71iE in-ear headphones (which both suffer from worn cables after years of use).
My impression after several months of use:
Pro:
* Great sound. Transparent but not overly trebly, which makes them suitable for longer periods of casual listening too.
* They are comfortable to wear. The over-the-ear cable routing does not cause me any trouble when wearing glasses.
* The cable is replaceable. The replacement cable is a bit pricey on its own, but when factoring in the time it takes to adjust ones ears to a different set of headphones instead, it will probably be worth it.
Cons:
* In-ears require frequent cleaning, and cleaning the IE 100 Pro takes me longer than it did for my old beyerdynamics. This is because one needs to pry out the little foam piece inside each ear piece with the (provided) tool beforehand. At least that's the recommended way, otherwise the risk of losing the foam pieces in the sink is just too high.
* The purse is a bit small and rather thin, so the headphones need to be handled carefully even when inside the purse. The cleaning tool and extra earpieces do not really fit in the purse.
* With the default rubber ear pieces, they do not drown out exterior noise that well (but one is free to use the silicone alternatives instead).
Overall worthy of five stars, yet with four stars for comfort (cleaning and carrying annoyances). Noise isolation is good enough but not perfect, so four stars for that.
