I had the same effect first 20 minutes putting on the hd600s i was like wtf is this did i waste my money. and then 1 hr later i was like holy shit okay now i hear it wow… went back the next day and sat for 3 hrs straight and i loved what i was hearing. love my hd600 because i also went from closed to open back. i just gave it time and that was it. no need for me to get an amp they are plenty loud with my lgv20 running uapp or poweramp depending on my mood.
Tin T2 Foam tips after like 2 years lol.