The Gieseking set I've got now is ripped from the redbook layer of the SACDs that came out a while ago. That is the best transfer of the material I've heard so far, but honestly the stream of it from various sources ought to good enough. I've got Amazon music's upper tier, the stream sounds the same as my rip. Gordon Fergus-Thompson made a great set in the early digital era, great sound on CD. The Amazon stream sounds wonky. There's a used copy on Amazon for a little over $18. There's another going for $900. You decide.