DAC for 500 Recommendations?

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..