My favorite headphones that I've owned in that price range are the Drop Focal Elex (exactly $600). I also own Hifiman HE560s (these are hard to drive), Audeze LCD-2 (you might find some used at that price), Audeze LCD-XC, as well as some high end headphones like Audeze LCD-4, Sony MDR-Z1R, and Sennheiser HD800. The Elex are comfortable, sound very neutral and detailed, and are well made. You can also find a lot of options for different cables.
Headphones $600 or less
Wife is working from home so I can’t blast the stereo system like I normally do. So I’m in need of a set of headphones have a budget of around $600. Need help I listen to classic rock very loud.