Yesterday, I noticed that my DT-990's broke. The sound became weak and somewhat distorted (particularly on one ear), and it seemed that there was some clipping. I noticed that the stress relief between the left earpad and the cable is a bit loose (though not broken), but other than that I see no visual signs of breakage. I suspect this might be an issue of a cable being broken inside the phones.
Do stores specialising in Hi-fi usually fix headphones, or am I on my own? What suggestions would you have for fixing this?