Are "vintage" DAC's worthwhile, or is this a tech that does not age well

Here's the right answer:
DAC's before 2010 were almost universally worse sounding with Redbook than with high resolution files. 

At a certain cut-off DAC's at all price ranges got universally better.  Performance with CD quality jumped up and digital glare and other issues vanished. I suspect this has to do with much more accurate clocks and anti-jitter technology in the underlying silicon. 
So for DAC's, not streamers, there's a real difference around this time frame.

The other part of this, music services. are more prone to changing.  If you can get a streamer that is separate from the DAC, and your DAC is at least post 2010 you can get state of the art for cheap.

Best,
Erik

Any one who thinks all DACs sound alike has tin ears. Sorry guys and gals but that's the truth.

@erik_squires Why 2010?

@jond
I have no idea.  I am only able to guess at changes and the date.  The big feature that is different pre/post this period (and 2010 is a guess due to lack of enough samples) is the sudden improvement in Redbook playback, and the vanishing gap between Redbook and high resolution files after this.

DAC's before 2010 were almost universally worse sounding with Redbook than with high resolution files.

i don't agree with this - it is contrary to my own findings