Updated 5.Sept. 2012: after the exchange there is only positive to report from the earphones. Of particular note is the excellent service, including accessibility, helpfulness and flexibility by the seller Music-Town GmbH Neubrandenburg. The problem with the first headset will be described below. The exchange included test lasted only one week.
Here is my original review. Better read that too ...
It appears now and then occur that an ATH M50 has a slight displacement of the acoustic center to the left, ie on the side where the cable enters. I had such a model and had it go back the next day with a heavy heart. This seems likely to be the exception and you should not be deterred from buying it. Search you can look for articles containing the keywords "Innacurate stereo image", "channel balance issue".
You can test the following:
1. Optimal with mono recordings. Otherwise, just listen to different tracks and pay attention to the distribution of sound in space. The relocation is relatively clear and in some posts I've read that with a 25% compensation by the amplifier, the balance can be restored.
2. If one perceives an unusual shift of the acoustic center in one direction, then simply turn the KH, so right handset to the left ear, etc., so that an "ear problem" can be excluded. After turning the shift to the right (also, always where the cable is) should.
3. To exclude the possibility that the source (ie the amplifier, the iPhone, or whatever) is the problem, you should hear the headphones with a variety of sources.
4. In order to be absolutely sure, you can also have the same title, where the shift has been found yet to test with another headset, here no relocation should be established.
As I said, that does not affect all models! The ATH 50 is top, only you should test according to KH attention within the return period.
Hope this helps.
Many Greetings,
Peter