i used to have an rDac, many moons ago. my system has undergone many changes since then, but I can say with some confidence that the RPi + Katana i currently use (with Isolator 1.2) would not only comfortably see off the rDac, but everything I've heard at three or four times its price. the Katana only just loses out to the Wadia 121 + Vecteur transport combination i use to play CDs.
Lenco L75 in a very heavy plinth /Hadcock 228 /London Decca Blue /Croft SMA IV Octal with separate 2020 PSU/ Croft 7R monos /Harbeth SHL5
Fletcher .3 /Hadcock 228 / Denon 103R/ Croft HeadAmp /Croft Mega Micro II (2015) /Croft Series 5 MkIi /Markaudio SOTA Cesti B
Leak Troughline III GTA / Vecteur D-2.2 / Wadia 121 / Katana, Isolator & RPi /RFC & AntiCable