What is the best used sub-$500 DAC?

I'd pick up a used MHDT Paradisea or a buy pre-built Monica 2. Both are very organic.

I have a DAC-ah - around $220 new - 8 parallel chips - NOS (non oversampling - filterless). Plenty of good reviews and fans of it here. But then I have not heard a lot of DAC's except I can say it sounds a lot better richer, deeper soundstage than my source unit's built in processors.

Second the MHDT recommendation. I use the Renaissance II. Before that had a Heart CD tubed cdp and the Lite Audio DAC60.

I second Tonyptony's EAD DSP7000 Mk.III suggestion.

I tried out even the Musical Fidelityunit that Sterophile went all gooey about, and the EAD was much better.

I heartily recommend the Oritek-modded Zhalou at this price point. It's sins are mostly of omission (and it has very few, for this price). Gives up a little extension, dynamics and life compared to pricier models, but hangs with much more expensive pieces. It replaced a Modwright P3A and Consonance 120 in my system.