I am not sure.
I have a Denon 3803 and it does not allow digital music to be played in Zone 2. I believe the reason would be that the DAC's cannot process 2 different digital signals at the same time. For example you want to listen to a movie in DD 5.1 in the main room - that occupies the DAC's, so you wouldn't be able to listen to a different digital signal through a cd player (for example)in Zone 2. Another source would need to do the DAC. I think thats why they are designed that way. I am not 100% sure with the 525 though.
Let me know if that works for you, i would be interested to know
