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

@drew_k ,
"When D/As became a $99-500 commodity, these design principles went out the window and the focus was on the chipset and general architecture (ladder, R2R, etc). The original designs put note emphasis on the “A” instead of the “D"

This is so true! Too much talk about chips and specification numbers.
Your entire post is on the mark in regard to what really matters in high quality DACs.
Charles

@drew_k ,
"When D/As became a $99-500 commodity, these design principles went out the window and the focus was on the chipset and general architecture (ladder, R2R, etc). The original designs put note emphasis on the “A” instead of the “D"

I concur and corroborate...

Anyway i own a low cost NOS dac Tda 1543 ....

There is no limitations on any count imposed by this vintage designed chip re-used in his own way by a french designer, no audible limitations in my audio system WHY?

Because the acoustic controls of the room is way more impactful than a dac, and optimize your audio system putting it on an another level completely, especially if you  did not use the  harsh analytical sigma dac on the market....

But like i already said:

Acoustic is the sleeping princess in Audio, but all people are looking for one of the working 7 dwarves....

The marketing schenanigans are more powerful than basic science....And the audio superstition around the listening of music from speakers .... We always listen music from the room....It is the last and more powerful piece of the chain....

I have 2 vintage Enlightened Audio Dacs that I really like for cd. As with most older units they have only digital coaxial and spdif inputs- no usb. Not a problem as I use them for enlightened audio transports. I have a Topping and RPI4 w/HIFIBERRY DAC hat attached- and both sound great for streamed music.  A $10k new DAC may blow all of these away, but since I don’t know I am completely happy with what I have. 

What a long thread in 2021. 
I agree with 80% of the comments and I really like the comments about the environment, room acoustics and type of music you listen. 
I currently listen to the current production Mytek, Berkeley, Hegel and also a vintage CAL master series mid 90s tube dac. 
First I would like to share that is so much fun and a privilege to have the opportunity to listen to music in different electronics. 
All my 4 dacs sound amazing with their different sound signatures. Once my ears get used to one, I start enjoying without thinking how the others sound and back and forth and on and on. 
The 3 newer dac’s seam to have more resolution, some more separation of the frequencies and the older on is more upfront and punchy and warmer, probably do to the tube it uses. But the kind of music does matter, and to me playing with different dac’s is like playing with different styluses on a turntable. 
Now regarding the initial question of the old dacs being worth it or not. A famous tech said to me one time that to make a proper dac the analog board needs to physically be large and also transformers size and type matter. So he believes that none of the newer dac’s that are put in small boxes are good enough and vintage ones that are build with the proper principals are better. But I got to hear to believe, so Im on the hunt for a vintage dac with the biggest analog board in the world :) 

Oh, another interesting one is that currently Border Patrol makes a tube dac and the designer choose to use one of the old Philips chip. People love this little and I still yet have to hear it in my system. 
All I can say is that all is relative and everything matters in a system but most important ti me is to get transported from listening to the equipment to start floating in the music. And all electronics that makes this magic happen to me are somehow divine. 
I thing that older dac’s are deffinetly worth looking in to as long as they are up to spec and none of their parts have gone bad with age and in that case bring it ti the right tech that will give it a second life. 
Do they say, that age is just a number ;). 

@jasonbourne52:

" All competently-designed DACs will sound alike. This applies to ones from 20+ years ago to the present"

Huh ? When I was shopping for DACs, I did home-demos of DACs from PS Audio, Heed, Metrum, COS and Aqua and was shocked by the dramatic differences in resolution and tonality. These differences appeared to have little to do with price (Units ranged in price from 1K to 6K).

I'm scratching my head as to how you could possibly arrive at such a conclusion. Or is it your contention that one must spend over 6K to get a "Competently designed" DAC?