I haven't heard the ue6000,but the 558 completely blows the m50s out of the water. The m50s are tinny sounding, with recessed mids and bloated bass. The 598s aren't necessarily neutral, as they are colored, but they are much closer than the m50s. They also have amazing mids, and I didn't find the highs or bass lacking, either. Unless you need a closed can, I'd go for the 558s.