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
Myself and two buddies had a DAC "listening test" at one of their homes.
All Rogue tube gear and Martin Logan with a USB feed from Roon.
Three DACs: Chord Qutest, Mytek Brooklyn+ and Bryston BDA-3.

Honestly didn't have to go past one track (Linda Ronstadt: What's New) the difference was so obvious.  Please don't bother trying to punch holes in the test or say it wasn't fair.  If your ears work you would have had to agree. BTW the order of DACs above was the way they sounded from
good to better to best. 

To the OP,  If you like the sound of an older DAC and you can be assured that it can be repaired if needed, then I say go for it.  Can't comment on any one in particular as I have no experience with them.

Regards,
barts
Post removed 
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.