I personally don't think the HD600 is for you. In my opinion, the Denon AH-D2000 is a better choice for what you want. It is a fun, refined, open sounding headphone with terrific dynamics but smooth response. I love it with all genres of music from Rock to Jazz to Classical.
The Denon is super easy to drive - you don't need an amp to power them (my daughter plugs hers right into her laptop and loves them).
but isn't the ah-d2000 a closed or semi-closed headphone meaning wont it sound a bit worse than an open headphone? Is there an open headphone you think would suit me better than the hd600?