@kman1211
A long time ago I also owned an HD600, which was somehow 'too smooth' for me - then I bought a K701, which brought more life into the music.
The HD600 then lay in the drawer until I sold it.
At the moment I listen with K712, K812, Austrian Audio Hi-X65.
I have my sights set on the DT1990 Pro, which I would like to try out. But the Beyer-Peak?
Neumann NDH 30 would be interesting but how far away is its sound from the HD600, is it basically based on the Sennheiser HD5xx, HD6xx series - also made in China?
The Neumann NDH 30 is a bit too expensive just for playing around.