For under $500, a used Teac UD-501 is your best bang-for-your buck DAC that can handle DSD. If DSD isn’t a concern, then a used Schiit Multibit Bifrost is very good value.
For something new that is slightly under your budget, the Denafrips Ares is worth auditioning.
For something new that is slightly under your budget, the Denafrips Ares is worth auditioning.