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


Hello,
whether it’s worth looking into old dac such as
Spectral SDR 2000,
Mark Levinson No.35 (36)
or so Sonic Frontiers Sfd-2 Mk2 DAC.

Digital audio is the fasted moving, now improving category out there
Because to this day they have no usb connection or other options.
But is it necessary?
Or is it better to still focus on a truly time-tested sound?

(sorry for my English)
128x128miglos
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...

😊
Doesn't matter what side you're on it has no affect on the DAC. It either measures beyond human audibly so you are hearing the other components in your system or it doesn't. DACs have been a solved problem for a while now of course this doesn't mean some companies create filters or add tubes to create what some term pleasant distortion. 
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Just ask yourself the question whether you would buy a 15 year old PC: there is your answer....

....most likely no asynchronous and certainly no high speed USB, no precision clocking, no DSD or high res decoding. All of this matters because you ideally want the DAC to slave the source to minimise jitter.