I had my HD598 for 1 month then I sold it because it has no place in my headphones inventory. The HD598s do have amazing value. They are so damn worth it for their sound. And yes they are not demanding at all. Feed them with average portable rig and lame 320kbps tracks they could still sound good.
Best Headphones ever b/c their amazing value? No... Those cheap-as-f*** Koss PortaPro may not agree. They have been sold well for several decades for a reason. Performance-wise, no. And they don't belong to the Hi-End category at all. Mid-range should fit. I notice that many people in this thread use portable devices as source. So for the portable rig, I have to point out that there are much better alternatives, Beyer T5p, T70p, Denon A100, Ultrasone Editon 8, just to name a few, and there are more. Yes, you need to spend a HELL lot more but they are clearly better in SQ according to my experience (I owned or have listened to all of them with proper source and amp,).
Excuse me for being ignorant, but as a high school student, these cans are too expensive for me ( not to mention a proper rig to make them sound good). It will probably cost no less than $1000 for that system. On the other hand, spending like $500 ( HD598 + e7 + e9) to get 8/10 or even 9/10 of their SQ, wouldn't you call it amazing value?