How old is too old for a Dac?


Been out of the loop for a good bit, and wondering how much things have changed in digital. In other words, how old is too old for a dac?
spoogemonkey
@ charles1dad

Makes sense. Though not sure how one would go about discerning one from another unless one happened to be privy to the materials used. 
Does anyone have an opinion of the Cal Audio Labs Sigma II? I’ve had one since I bought it new and have always run it with NOS tubes and loved it but I’m wondering if one of the newer DACs under 1K would be better due to the age. I'm particular to tube-based to tame digital for my ears.  It’s not real easy to audition something like this since they have to be ordered online most of the time.