Best used DAC 500 or less, need help

Tim is right...the Millenium DAC 2 uses Ric's own output stage...no cheap op amps. It does use the Crystal Upsampling chip which must reduce jitter, because I'm using mine with a Studer CDP from the late 80s and it sounds amazing. I also second his opinion about the Apogee Wyde Eye Digital Cable for $30-$35...no matter which DAC you choose. They're incredibly musical and unbeatable at that price. I honestly think you have to spend more than $250 (or maybe $150 used) to buy a better digital cable.

I also second the opinion on the modified MSB DACs, and I'm sure the Meridian are good too. I'd also keep an eye out for used Assemblage DACs.

Audiolab 8000DAC or even better the DAX. This is not a bright DAC but gives a very nice natural tone with good stereo. As a bonus it reclocks the input data to remove jitter ... this is probably essential unless you have a high end transport.
New they were about $1000 but for some reason they seem to come up used for $200-$300.
Depending on your transport's jitter reclocking will be very important .. either get a reclocking DAC (most older DACs do not !) or budget for a Monarchy DIP between the CDP and the DAC.

I found an EVS Millennium DAC 1. I'll let you know how we did when it arrives. Thanks for the help!