I recently bought the beyerdynamic DT 770 PRO 80 Ohm headphones, and they're worth it. beyerdynamic being so well respected, I went for their DTX 101 iE Earphones, they look great, feel fantastic, no comfort issues. But In my opinion they sound terrible. My 15+ year old Aiwa Sound GT earphones sound better. They sound dull, flat and lifeless.    FYI they also hiss badly with my portable headphone amp (FiiO E11). These are low impedance, so an amp is not required at all.