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

DACs sounds differently. Depends on chips used, codec, technology and resolution supported. DACs r different animals... DSD, MQA, tubed or R2R... all of them sounds differently and vintage too. 

I own 4 DACs- a mid-90’s California Audio Labs Alpha (tube amplification), a circa 2010 Halide Designs, an Audioquest Red Dragonfly, and a Schiit Yggdrasil GS. The Cal Alpha was renowned in its day for being analog like, and it’s sound remains pleasant. The Yggdrasil totally smokes it in all regards, it is profoundly more transparent with better dynamics and imaging, while remaining musical. I would be astounded if the average person off the street wouldn’t immediately notice the vast improvement of the Yggdrasil.

This thread is reminiscent of a certain Julian Hirsch, possibly the worst and most deluded audio reviewer of all time. His ears seemed to be filled with lead. His “Hirsch-Houck Labs) in his basement lacked equipment to measure dynamic features of amplifier performance, so he likened the measurements of slew-induced distortion and TIM distortion, both major advances in addressing how amplifiers actually perform, as “belief in the Easter Bunny.”

I guess that I am really tired of the willfully ignorant who claim no differences in gear when any modicum of listening or testing will show that they exist.

Testing shows most DACs don't have sonic signatures as long as they conform to basic engineering principles. I'm tired of the willfully ignorant who dismiss standard testing protocol and crown themselves golden ears. 

I own several DACS . Some current and some Vintage.
Not to promote one against the other. i.e. My Krell SBP 32X sounds way better then some of todays moderately priced DAC's.
The ones you're considering are very good. If you can get them at a reasonable price (Check some of the reviews behind them) you will be very satisfied.

Testing shows most DACs don’t have sonic signatures as long as they conform to basic engineering principles. I’m tired of the willfully ignorant who dismiss standard testing protocol and crown themselves golden ears.

I apologize for being in total opposite side from the "gold dial" side...

Dac dont give the same sound in all environment, like amplifier or speakers...Dacs are not like one another at all like other piece of gear...

The only way to test a dac is creating the rightfully controlled environment, and in this environment a good dac will disapear to some degree....Like other piece of gear to some varying degree related to the quality of their design...

My 20 bucks dac bought with a bid on Ebay give me ALL qualities associated with great dac: imaging, details, holographic sound, even analog flavor and is so good that upgrading it seems silly and dangerous idea...For those who think my S.Q. because of the lowest price of my gear limit my experience, my system for his price rival anything which top him for sure but not being so distant behind that most would think...

I deduced from that 2 things: there is difference between dac, and a good dac COULD or CAN cost peanuts and give a totally satisfying acoustical experience if the environment is under control in his 3 working embeddings dimensions : mechanical,electrical and acoustical....

I know most will not believe me....

Pricing a design means that often it is a better one but there is a ceiling where the implementation of the design begins to be way more important than the electronic design sophistication itself....

A controlled room is the more precious part of any gear at any price...