Well, without having any technical basis, just mathematician intuition, my notion would be to let PS Audio / Ted Smith processes upscale 16-44K PCM direct to DSD, instead of having an interim PCM level provided by other gear. See Ted’s comments in Upscaling before Directstream? - Audio Components / DACs - PS Audio. But I have to admit that I do not know jack about “Rob Watts’ unique filter technology”. Though Tom Stockham himself told me in the late 1980s that 16-44K was not picked only so as to fit Beethoven 9 on a single CD disc. It was also because humans could not detect better. But, yeah, that was with equipment from like 40 years ago…