I have exactly this problem. The left headphone became quieter and quieter. This problem is very common if you look around a bit on the internet. But a friend of mine also bought the IconX and now has exactly the same problem as me. I have also often read that this problem occurs again with the exchanged headphones. The headphones are fine as long as they work, but I would consider an alternative, e.g. from Bose, as this is a defect that is extremely widespread and Samsung does not react to it. The infrared sensors that register whether the device is in the ear also tend to go haywire, another minor criticism.

I bought these headphones a few months ago and am absolutely satisfied. The sound quality as well as the ease of use and the long battery life justify the price.

I also have this problem...After sending the headphones to Samsung support, they worked perfectly again - for about 1 month.
Gradually, I have lost the joy of these headphones, they are also not exactly cheap. Therefore, I am considering sending them in a second time, but I am inclined to switch back to conventional in ear with cable....