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
@tomic601, Hi Tom, may I assume you own or have owned the 'Pandora' and if so what did you upgrade from and have you ever heard the Mojo Mystique kit. The superseded V3 interests me at about 50% the cost of pandora. 
i would think any over priced DAC Would still sound better than a  under
$1 K.  DAC  of today , 4/2021         NO!
Classic Statement , 
  In controlled A/B tests nobody can distinguish a $100 DAC from a $1000+ one. Try a PeachTree DAC It.  to a  low priced Schite Audio DAC   many examples Borris,  listen to a Audio Quest Dragon Dac to a  Small Beater 
And a Good day to you Sir