Hey people. Since I have recently made a journey to finding the right combo for my ears I can honestly say that the best thing to do is to analyze very carefully what it is you really want for audio reproduction.
Me personally I like many types of music and the HD600's are well suited to many types of music so they were a good choice. I wanted to hear things as if I was there, I wanted to hear every detail on the recording because that for me would be the closest thing that the recording could offer to reality. But at the same time i wanted it to be MUSICAL, I didnt want to be blasted with digital harshness...
Sometimes the combo is so revealing that recordings you once thought sounded good enough to listen to now sound very crappy and hurt your ears. COmbined with the Melos the level of sonic resolution is so high that on some cd's I can actually hear that the sounds I am hearing are not music but compressed digital noises recorded onto different tracks and pressed onto a cd. Do you really want this? The thing is, with well recorded cd's, particularly cd's that undergo the smallest amount of studio time, the sound is so real and stunning you will be breathless. You will also see that you cannot EQ your system to get a hi-fi sound.
For me the only way to get sound that satisfied my need to BE with music was to get very good headphones, and a very, very good amp. Having these two things will show you how close to real the sound can be... And once you have these things you will see that you can hear strait into your cheap ass cd player, and you can practically hear the bits getting lost inside it. SO you come to realize that the most important thing really is the SOURCE. And that without a good source all your other efforts are only to show you how much your current cheap ass SOURCE is leaving behind...
So its a circle of sorts, you will not trully appreciate the headphones or any other part of your system until they are all at equal levels. So buying the HD580/600's isnt really a question IMO. The question is what will you do once you have them???