The DT 990 Pro is far inferior to the DT 990 Premium 600's. They have more upper bass and a sharper, less broad mid treble peak and muted upper mids with the net result of a muffled sound with a treble tish. I honestly couldn't stand the Pro's. I loved the Premium's, though. I like them just a bit less than the Denon AH-D5000, which, in turn, I rate a tad less than the DT 880 Premium 600's.