So the conclusion was that the same CD played through the R26 sounded more or less the same as when you played it only through the Onkyo only? That implies that the R26 isn't the cause of any sonic differences you're hearing.
Make sure the volume is matched if you try to compare the streaming service against the CD player. Even a small difference in volume can make you prefer one over the other.
Finally, keep in mind that the streaming service can have a different version of the same recording in their library. If you want to test your streaming playback chain, I suggest ripping the CD to FLAC, streaming the files through the R26 and comparing that against the CD played through the Onkyo.