To be honest with you, I think Hifiman Edition XS might be the best headphone in the $400-500 mark. It has a truthful and neutral presentation with great decay and transparency. It’s not too hard to drive, and it certainly has what it takes in terms of being a reference headphone for the price.
Sure, there’s always a superior headphone out there and there always will be, but if you’re not willing to spend huge amounts of cash for an open back headphone for your desktop, it would be difficult for you to find a better option than the Edition XS.
I will never argue with any of the many who already consider the Edition XS as one or possibly the best headphone at or under $500 because it would be foolish of me to disagree. In fact, I’m on their side and totally agree.