The R2R topology is the means to acheive No Oversampling, and apparently most R2R dacs marketing NOS (denafrips) actually are not.
Not silly if PCM192K(whether it is upsampling or naive data) and above if I remember. You do not need a filter. There was big thread about this under a review of a certain DAC review.R2R D/A converters do not necessarily involve no oversampling. NOS also does not have to be filterless. But filterless is just silly stuff.