Welcome to Hifiguides @Kayge hopefully some of these recommendations are helpful
Tygr 300R: newer headphone from beyerdynamic. Warm, smooth, Relaxed, wide and speaker like. Think the dt 990 but instead of all that brightness it is now almost completely balanced on the treble but keeping all that detail and smooth sound with a comfort to the point it disappears off your head. You can find my review on this one over in it’s particular thread 🔶 Beyerdynamic TYGR 300 R
Nighthawk/Nightowl Carbons: Dark / warm bassy detailed veyr unique. Discontinued but can be found time and again… difference is open back and closed back I own the nighthawks and they are really incredibly nice and definitely good for someone who is treble sensitive
Fidelio X2 HR: philips made a pretty nice bassy headphone here again very warm very smooth bass may be seen as “muddy” they are currently making the X3 so this headphone could drop in price even more
Dan Clark Aeons: These are pretty unique as while they are a V signature they are by no means very bright. The treble is actually rolled off with mids not being very recessed. Very good tune to this headphone. Responds well to higher end amps and dacs as well as being balanced through a seperate cable purchase. Tuning pads allow you to adjust bass, treble, mids, and sound stage. Retuned and Massdrop open x are in your price range
Step ups from 58x are the 6xx, hd 600, hd 660 S and further up though each has a seperate sound I believe iirc 660 S was the brighter headphone though so may not be up your alley on that one.
Step up for the HE4xx would probably be the Massdrop Edition XX which is the ananda but not as bright and more warm
Audeze El-8 has multiple copies but they have a rolled off treble and are more towards a dark kind of sound. Still really nice sound.