600 ohm version is one of the best headphones money can buy for things like dubstep, techno, and quick changing beats. The sound can be intense, so if you want flatter, more subdued notes, you may prefer the DT880 600 ohm. These can be powered with on board audio, but will go louder and sound better with an amp. These are one of the best commercially available headphones ever made.
I have both - and in my opinion the 990s are far more "fun" to listen to - makes music listening more enjoyable than on the 880.
Note: Both of these require a good amp. My testing on a Meier Audio Corda Classic, after an Abrahamsen DAC.