DAC for 500 Recommendations?

I'm looking for a DAC for under 500.00 used that would be a great buy. Someone said the inexpensive Adcom is a stellar buy. Any suggestions out there?
The EVS Millenium 2 is flat out stunning. I had one in my system,and it was incredible. They occasionly pop up on Audiogon for 500.00-600.00. I tried the Adcom,and there is no comparison to the Millenium 2.
Thanks for the response. Which Adcom did you get to demo? Did you do it in home?
I also second the Millenium 2 if you can find one (maybe a Millenium 1 too). If not, you can buy a new Ack dACK! for that same amount. They are also excellent with a different feel and design approach. I am not familiar with the Adcom, but the dACK! should be superior to any mass market product in that price range (I would actually consider one if you are spending less than $1500-$2000). Like the EVS Millenium DACs (were), they are handmade and sold direct by the designer. They use quality parts that no mass market item could afford to use in that price range.
KCdrummer- It was the original Adcom 600 processor. In my system I couldn't hear a difference with/or without it. That was in my system-I have heard of others who liked it. Yes I did try it at home. The Millenium 2 at the time I had it was the biggest sonic upgrade I ever made. I was using it with a Pioneer DV-37.
The Muse 2 is showing up for that price as well. Former S'phile Class A. Look for one with the Bessel filter and HDCD options.
Consider picking up a used MSB Link DAC for +/- $150 and send it to Dan Wright and let him improve it for another $250+. See more info at www.modwright.com
I had a GDA600 DAC by Adcom. Nothing to write home about. It was a little too smooth and lacking in details, but was good for taming a bright system that I had at the time. A MSB Link III (never heard the earlier ones) would be a significant leap over the GDA-600. Remember the GDA-600 dates back to about 1994 or so. So it is pretty old at this point. A modified MSB or an EVS DAC would be a significant improvement over the stock MSB in everyway.
I see lots of Bel Canto DAC 1 or 1.1 going for around $500 lately. I've never heard one personaly, but I hear from others they are supposed to be good.

Then, there is also the ART DIO smart mod frm boulder cables. that would still be under your budget.
I've got a ART MENSA Plus coming from them soon...can't wait! That is their premier mod and it is only $500 on top of the $130 pricetag of the DIO
Timbre TT-1

Former reference DAC for one of the audio houses. Very 'musical.' The wholesale value of the raw parts alone is ~$1200 in mid to late-90's dollars. Often compared w/ the big boys..