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

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...

I wouldn’t put much money into an older dac.  I had a lovely theta basic and had it serviced because the power button and a sources selector button were inoperable.  I don’t recall the price but it was very high including shipping:   Also a notice that they would no longer support  the device.  The chip will last forever, the supporting architecture will not.

The problem is solved for me because my contemporay dac include only one vintage chip Tda 1543...

😊