How old is too old for a Dac?

I believe that for redbook CD playback via transport or as uncompressed files from computer or server, use of an older DAC with an excellent power supply and analog output stage at a fraction of original cost seems appealing to me. Of course, with the computer use of a USB/SPDIF converter would be required.  I am about to try a used Bel Canto DAC2 in my secondary system.  Currently use a Bryston BDA-1 in my primary. 

As Bigkidz stated, considering DSD digital is different. 

H I Jond,
What differences are you hearing via further listening to the Audio Note and the Yamamoto DACs?  I'm assuming this was a fun and informative comparison. 
Charles 

Charles to be honest the AN keeps getting better by the day I haven't been able to take it out yet! I I am pretty convinced the AN is considerably better than the Yamamoto but hearing being fickle I will give the Yammie one more listen before I decide.  Off to NYC for the weekend so that will likely be next week or weekend.  There is just something so right about the AN though I feel very fortunate to have won that auction now!
Cheers,
Jon

Jond,
I'm not surprised that the Audio Note is impressing you,  it has been highly praised for many years.  Excellent design and implementation withstand  the test of time. No doubt that using Duelund CAST as my output coupling capacitors improved the Yamamoto DAC further.  I'm certain that I'd be just as impressed with the AN DAC as you are. Congratulations. 
Charles 

Spoogemonkey, I think you are wondering if you buy an older DAC, how far back can you go?  I would say that unless you select a DAC that was $5000 plus new, you probably shouldn't go back more than about 5 years. 

As noted, there have been massive improvements at the lower price points from about 7-8 years ago, and this improvement still continues, although improvements are slowing. Arguably, the best sub $500 DACs today, would probably compete with most of the sub $5000 DACs from 10 years ago. 

Take a look at Bryston, Ressonessence, Chord, etc. The younger folks seem to really like Schiit, Brooklyn, Woo Audio, etc. I just got a deal (more than 50% off) on a Meridian Director so I thought I'd give a try.  With just a few days to listen suggests it is pretty good for the price point. 

spenrock