What is the best DAC to buy used in the $500 range

I am looking for suggestions on the best sounding used DAC in the range of $500 used. I have checked the archives but didn't find any useful information. Does anyone have any suggestions on what to look for? Thanks for the interest.
pubstub, patience is the key. The Forum has much, much useful info. Go into Forum - Digital and just start reading. Also, as you're working your way thru, go into the Digital sales area and review the suggestions and the items that junp out at you. You probably won't get your answer in a night, but over a week you will be alot more versed and probably looking at specific makes. But have fun. Dave
Why settle for used. You can get a new Audio Mirror D1 DAC for $500 new on Audiogon (sounds like 3 - 4x the price). I just bought one and am thrilled with it. One note, it is non-up/oversampling so if you're not into that philosophy then you'll need to consider others. Doing my research I have seen great products from Scott Nixon, Bel Canto, MBS, Ack,and others in your price range. Look around and do some research and I'm sure you'll find what you're after.
Pugstub, the world is your oyster in that price range. Musical Fidelity make the A3 24 which sold for $1200 new and can be had for around $550.
EAD made the wonderful 7000 series III that I've seen go for around $450 and sold for almost $3000 when new.

There's one thing for sure, at the $500 level, if you buy it and find that you don't like it, you can likely resell it within a week or two and not lose a penny.

Be bold, read a few threads and take the plunge!

the $500 dACk (Version 2) that was just listed a few hours ago probably has little or no competition at that price. I do not know the seller or his particular DAC but I know many people who have had great success with the earlier versions.
Italian has good advice if I may say so--the question, "What's the best unit for X dollars?" has so many answers that it is really not too helpful. The data you can gather by listening is the most reliable, but if reading is all you can do, it's a good idea to read around the central question, finding other answers as you do, and new questions.

Also, if you read the Digital forum as suggested (here and at Audio Asylum), you will find some good ideas hidden under titles that don't seem like what you're looking for.

And yet, all that said, I can't help starting the inevitable, confusing list of specific recommendations that may end up to be a yard or so long. Here it is: Apogee pro gear is sleeper. I have an Apogee DA-1000E and it cost around what you are willing to pay.
audio note
I can tell from having the Birdland Audio Lite dac from the time it came out til now that this dac is great.If you want a smooth sounding dac with lots of detail this is it.Do your self a favor and read the reviews.
I was in the same situation 6 months ago and my research lead me to the Bel Canto DAC rev 1.1 - the .1 is an power supply upgrade from the original. The BC DAC retails for 1300.00 and they can be acquired on A'gon used for 500-600 dollars. Do a google seach a read the reviews -the BC is an excellent performer

NOTE....which ever DAC you settle on be sure to pair it with a high performance digital cable. When I initially purchased my DAC, I bought a well reviewed budget digital cable and at the time though it was a good performer...that was before I auditioned a Transparent digial reference cable -the difference was night and day. I never would have imagined that swapping out 1 cable would make such a difference, but it does, at least with my setup the diferrence was audible.

Good luck!
please disregard the subject line of my previous post "rotel rb-1080 hmmm" looks like the line was copied from a previous post. The line should have read Bel Canto Dac 1.1...thks
I second the Ack dAck recommendation. I have it and have compared it to a few high $ units (Cary, Meridian) and it comes through with shining colors. Terrific analogue-esque sound. The new version is supposed to be even better, but for the $450 or so you will pay for a used one, I think it is a true audio bargain...
First, decide on what features you need, volume, toslink, coax, multiple inputs, hdcd or....
Secondly, do you want tubes or solid state?
Third, do you like warmer sound, analytical or ???
Fourth, do you need 24/96 or will a great 20 bit unit work?
Finally, looks: Do you need it to match your system?
The Audio Mirror D1 DAC is awesome. I'm glad I bougt it and am considering selling my Nixon and buying another one.
You'll rarely see a Scott Nixon tubedac for sale and there's alot of raves about them. New ones are around your price. I've not heard it but several people I respect have told me it's outstanding. Definitely worth checking out.