You are right on the spot. I think I'm asking for too much at 500-600 price point
No, it's not that you're asking for too much, it's that you're basically asking for a headphone that has no flaws whatsoever. There are plenty of fantastic headphones at the $500-$600 pricepoint, but even at double or triple that point you're not going to get "flawless."
I guess what I'm struggling with is in between HD600 and HE400. Could anyone comment on the sub-bass of these? I have a E17 to drive during my travels (in the hotel room etc) and also Yamaha V671 for my home office use. I liked K550's sound stage and airiness it was just the bass was lacking and making the sound hmmm "not fun?" I think I'm almost there to make the final decision, just need to decide in between these 2
I still think the K1000 would be a better candidate if the K550 were "almost there" - the Sennheiser will have a somewhat rolled-off top-end by comparison. I haven't heard the HE-400 to comment on them.