DAC recommendations

Lately I have been using my PC to play music in my system. Reason is that my NAD broke so I have been using my PC. Since I have all my CDs rip to wav format on my computer, I have been thinking of getting a DAC with USB connection. What DAC do you recommend for under $600? Thanks
+1 PS Audio DL III
CI Audio VDA2/ VAC1 second hand.
Schiit Bifrost...
Peachtree DaciT
if you can find a used one at your price, consider the original minimax sabre dac.
You can buy a used Minimax dac, and upgrade opamps later.