What source(s) are you currently plugging the headphones into?
What DAC and headphone amp. are you using?
Try putting the K550 under a blanket for a few days while plugged to something playing audio at a higher level then you normally listen to.
I prefer to play Metal for burn-in audio.
Indeed, the OP must tell us what the source is and if lossy compression was used. This is critical before saying a headphone (or speaker) is crap.
Then, what's the amp ?