Sitting here listening to a pair of PCM-63K's in my 25 year old Dac and things sound better than ever. I concur with above sounds like salesperson agenda BS.
Downside to R2R Ladder DACs?
A sales person I generally trust told me to steer clear of used R2R DACs, since their reliance on high precision resistors causes them to sound best when new, and degrade fairly quickly. It seems reasonable; have others had any experience with this?