I've used my Sennheiser HD 598s lovingly for about a year or two, and I'm finally craving something different and a bit better. I've been looking since about November on and off (obviously not the whole time), but been unable to pick something. Mainly since I can't preview how cans will sound, and so I worry if it won't be a noticeable difference and will be worth the money. While I'm overall extremely happy with these cans as my first relatively non-cheap audiophile set of headphones (which also unfortunately doesn't give me much to compare them to) I certainly could be happier.
My budget is at about $200-$400. My main issues with the 598s is that some music seems to be lacking. I'm a fiddler and plain fiddle often does not sound too impressive, and other types of fiddle such as nyckelharpa and hardanger fiddle do not either. In some more complicated acoustic music a lot of instruments seem to blend together too, and it can be hard to pick out a harp from a nyckelharpa from a fiddle from a mandolin. In addition, the lows are noticeably not very great (though of course mids and highs are more important and I overall care more about). A song with acoustic guitar, maraca and jingle bells will have invisible hand percussion in the background.
I was looking at the ATH-AD700X in particular, and a bit right now into the AKG Q702. The AD700X sounds from reviews a lot like I want: beautiful strings, great soundstage, no blurring together of instruments, works on a variety of music such as traditional folk, classical, and black metal. The AKG Q702 from reviews sounds fairly similar, but with a larger soundstage and a bit more expensive (about $60 more from what I saw, here in Canada). However since these are so similar in price to my 598s, I'm not sure they'd be both a better sound as well as a different sound closer to what I want. A lot of criticism to some headphones will mention bass, and so I'll mention that I listen to almost no music with bass, and so it is not a priority. The last thing I'll add is although I think I'd prefer a more neutral sound that is close to the source audio, the neutrality of my 598s can sometimes seem to be a bit dull. I find I rely on slight, precise adjustments in an equaliser to make it sound more listenable, usually in a bit of a V shape with a bit of favour in treble. Maybe I'd like fairly neutral, but not too much?
Would anyone be able to advise me on a pair of cans I'd like and wouldn't regret? Any help is much appreciated.