As long as you have a transport for the music, and can plug it into the Yggdrasil and then plug the Yggdrasil's RCA outputs into your Grace preamplifier's CD or Auxiliary input OR the balanced Yggdrasil outputs into your Grace balanced inputs, there should be no issue that I'm aware of.
If Schitt is saying the Apple device will trigger the "lower spec," then it can be assumed you will hear the music under less than optimal conditions.
If Schitt is saying the Apple device will trigger the "lower spec," then it can be assumed you will hear the music under less than optimal conditions.