Is a femto clock important if you aren't using asynch USB?

I like buying used but never do it with Digital gear.    I did buy a R2R DAC ,  but I also have a DAC that can do DSD.     When I bought my streamer I wanted the latest tech and codecs.     I am a late adopter when it comes to everything else.....

Some DACs like my RME adi2 always use their internal clock regardless of input type.   It's Femto clock is used also when there is a Coax or Tos. Input,  it doesn't just use it's clock for USB.

The better the internal clock, the lower the DAC's jitter rejection can work, to a point.  If upstream jitter is extreme enough no internal clock will fix it.

I agree though that chasing a 10 year old DAC seems imprudent. That was just after the cut-off range, when I remember Redbook playback getting much better.

I had a W4S Dac 2 (not DSD).  It was the worst sounding standalone DAC I have owned.  I would pass.

I have an old W4S dac2 and it is indeed a good dac if it works in your system.  Since you're shopping in this price range, I doubt you'll hear the difference with or without a femto clock  (this was a flagship dac over a decade ago but worth a couple hundred dollars today).

Be aware that the Dac2 is not driverless.  I got it work fine with my bluesound node but then Roon will not see it.

Jerry