Have you tried switching the left and right of the cable or using another source to rule out a cable/source problem? (For EL-8s, you’ll need to flip the connectors so the L and R are on the outside. Otherwise the connectors can be damaged and this isn’t covered under warranty.)
If you've swapped the cable and the problem moves with it, the problem is either in the cable or the source. It it proves to be the cable you may need a replacement cable. If it stays in the same ear, we know the problem is in the headphones and you'll need to proceed with repairs either through us or via an international distributor.
If you bought through a dealer, we recommend contacting them for service assistance.
If you live outside the US and purchased locally, we recommend contacting your dealer or our local distributor for assistance. You can find a list here: http://www.audeze.com/dealers-list
If you live outside the US and the headphones were purchased from within the US, please email us at firstname.lastname@example.org and we’ll take care of you.