Cool! This definitely comes down to a taste/hearing thing. Having listened to dozens of earphones, and having once owned and rather loved an Audeze headphone, something I realize about myself is that I enjoy having a somewhat laid back 2-4 KHz region like the OG CRA and the EDA Balanced, and having once owned and loved/hated a DT 1990, I actually like a slightly elevated lower treble. The CRA and EDA Balanced walk that line of nearly too much treble without ever stepping over it.

So looking at that CRA+ graph, I see a couple of things I don't like:

1. Increased energy at 2 KHz
2. The somewhat typical 6 KHz dip that definitely avoids sibilance but usually makes things sound kind of boring and muted for me

I got mine from CUFOK Global Store.

Yeah, I got these because I wanted CRA with less subbass, and I got exactly what I hoped for.

The biggest difference is that the HD600 is much more forward in the upper mids around 3 KHz. I'm pretty sensitive in that area, so it makes the HD600 unpleasant at higher listening volumes. A lesser difference is that the HD58X has better extended and tighter sounding bass, though that might mostly just be because I can comfortably listen a bit louder than with the HD600.

It's been years since I've had the HD600, but I would say that on treble quality (extension and evenness) the HD600 is probably better than the HD58X, so if you listen to a lot of acoustic music, especially string instruments, and you don't mind the shout around 3KHz, the HD600 is probably a better choice.

Agreed. I've owned HD600, HD650 and HD58X and the 58X is the only one I've kept.