What is the best used sub-$500 DAC?

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.

Thanks for all the responses. i'm usng a trends audio class t (TA 10.1) amplifier and a pair of tekton design 6 inch fostex full range speakers and plan to replace the amp with something low powered and single-ended. what about the venerable CAL Sigma? is it competitive anymore? thanks again for all the options...just what i needed.

Nhtran: How would you compare the sound of three units you mentioned? I am very curious, thanks.