I believe there are some trickle-down technology benefits from some of the companies that offer megabuck phones, i.e. Focal, Hifiman, Sennheiser and others, in their lesser-priced models. I would start with used phones in my price range and move up from there. Try to hear as many as possible before buying the pair you will probably use for many years. In my experience, I started with Stax Lambda, moved up to Lambda Pros years later, and now use Stax 009s w/T1S tube driver unit. Again, try to buy phones you believe you can live with for many years. You can always upgrade later by adding a dedicated tube amplifier when your budget expands.