Under $50k is going to be very tough. I'd increase budget to $250,000 and cover your bases.
Is it possible to find a good DAC for under $50, 000?
Apparently, the good folks at The Absolute Sound have you covered.
https://www.youtube.com/watch?v=nItR8Z6CCWE
(Audiophiles are never going to shed their out of touch reputation with journalism like this. I'm sorry, but it's just so tone deaf.)