The 598s may be a bit slow but they are definitely not out of their league in the company of the HE400s. Both headphones have a place in my collection. For metal, most harder-hitting EDM and some larger scale orchestral stuff, I'd reach for the HE400s. For slower rock, prog rock, small scale jazz, chamber music, acoustic/vocal stuff, I'd go with the 598s. 598s for gaming too.
The Hifimans are impressive played loud with loud music and have a brilliant, textured bass, but they don't have the liquid smooth midrange of the 598s, nor the comfort or soundstage.
I agree 100%. I had 595's, which I would imagine are pretty similar to the 598's, and aside from losing in bass, they were excellent cans that I wouldn't trade for he-400's. that said, there would be room for both.
but with my hd-650's sound like my old 595's, only with better bass, and better in every way, there's no point for me to touch the he-400's. the sub-bass is all i gained. the echo'ing in the cups, and the harsh highs killed it for me. modifying them to get them tolerable isn't an option. what if i do the mods and still don't like them? then i won't be able to return them. hence why they're going to the ups store today.