Don't get an MM-500 for just music enjoyment. They're designed for mixing and mastering, with no colorization of the sound. It's designed to be flat, a magnifying glass only of what was recorded.

You say you record and mix music, so the MM-500 could be good for that purpose. but I think you would be better off buying a good $300 mixing headphone for your composition work and then a quality $1,500 headphone for musical enjoyment. Goldilocks doesn't really exist in audiophile headphones.

While that sounds pure and honest on the surface, most of us want some sort of sugar or spice added to our frequency curves. Pure can be beautiful; it also can be boring or expose recording warts you don't want to hear.

I don’t understand the benefit to any headphones that don’t have a good balance of dynamics. Like, so much of music is that.

Perhaps ambient, classical, jazz could benefit? I didn’t realize there was this much nuance to this hobby!