Which open-backed headphone do you recommend out of the box? ie no EQ.

[kemmler3D]

Clearer, better separation, bigger soundstage

Look for headphones with minimal distortion (some planars are very good for this, like the LCD-XC), and/or with angled drivers or different ear cup shapes. That's about what you can do when it comes to the headphone itself, without using EQ.

As has been said about 50 times, EQ is also a good idea.

Lastly, you should try crossfeed. IMO this is the most reliable way to improve stereo image with headphones. What I finally accepted is that headphone sound is fundamentally unnatural, because in real life, it's very rare for a sound to be heard by only one ear at a time.

This makes the stereo image very Left-Center-Right, in-your-head-sounding.

With crossfeed, some of the left is mixed into the right, and vice-versa, more like how speaker listening (or any other kind of real-world listening) is. IME this makes the stereo image from headphones much more realistic.

There is a free plugin you can use to try it: https://resonic.at/tools/bs2br

 

[solderdude]

I don't know...just "better." Better sound. Clearer, better separation, bigger soundstage...I don't have any specific complaints about the HD650, but...I didn't have any specific complaints about my Dragonfly Cobalt either, but when I got an Okto Research dac8 it was clearly "better." Better resolution, I could hear more fine details, the music sounded more realistic. I'm hoping for a change like that.

Below are some open models that may fit your bill in various price classes you may look into. All can improve a bit with EQ

OLLO S5X (is not for everyone)
Beyerdynamic DT1990 (with treble filter or EQ)
Sennheiser HD490 PRO
Beyerdynamic DT900 Pro X
Sennheiser HD560S (>2022)
Sennheiser HD660S2
Neumann NDH-30
HIFIMAN Edition XS
HIFIMAN Sundara
AKG K812
Audio Technica ATH-R70X (may not be able to get a good fit)
Focal Clear
MonoPrice M1060

These all sound somewhat different (not necessarily 'better') but not too far off from the HD650 tonality which is not bad and would have been in the list above.

 

[InfiniteJester]

With crossfeed, some of the left is mixed into the right, and vice-versa, more like how speaker listening (or any other kind of real-world listening) is. IME this makes the stereo image from headphones much more realistic.

HeSuVI for Equalizer APO is free and allows not only AutoEQ presets, but very different kinds of surround virtualizations that I personally enjoy more than regular crossfeed; particularly when watching movies.