These are the two headphones I have on my list at the moment. I understand that the HD580s are quite old and I would have to buy them used, but they are basically the HD600 without the ugly faux-marble finish. I'm not sure about the HD580, but I've read that the HD598 are a very fun can to listen to -- very large soundstage. My main genres will be rock based and classical. I do not have the option of trying either out.
These two are roughly the same price, so that's not really a factor. Any recommendations?
Note -- I will be using my Schiit Asgard as an amp and my computer (HT Omega Striker soundcard) as the main source... still looking into a dedicated DAC.