The HD650/600 are often described as slow. They aren't, they just have a dynamic bass and a rather warm signature. You would probably call that punchy or snappy. The K701, HD800 and the DT880 on the other side are very clean sounding headphones, but they are also very compressed.
Do a side by side comparison with the ATH M50 or the Shure SRH 840. There's almost non compression in these phones.