From what I know the SD card associates itself with the Pi via the issued password for the SD card and an internet connection back to JRiver home base.
If you change the card to a new Pi, you'll have to go through the registration process again and you'll find that that task burns a licence credit. I think you get 10 or 12 goes per year.
I've got the
502DAC. It's recognised as a Hifiberry DAC, so the IdPi plays nicely with it. Do you know what the story is with the PI2AES - Pro in that regard? If it's a special, then you may have a challenge ahead getting audio out. Better to avoid messing about with the
Device Tree if you can avoid it. You could confirm that detail with Pi2design and and see what it's equivalent to. Then check back here with the dt overlay detail that the PI2AES uses and confirm that the equivalent functions well with another user.