Hi res audio through airplay

My set up comprises a NAD D7050 driving a pair of KEF LS50s. Based on my little experience, the system sounds great. I play mostly ALAC music store in a NAS through DLNA and Spotify Premio through Spotify Connect (directly through the D7050 controlled by my Ipad).

I am now in the testing period of a new streaming service (at least for me) called Classics Online DH-LL, through an app installed in my Ipad. The fact is that Classics Online claims to transmit Hi-Res tracks and I wonder if when I am playing them using airplay directly at the D7050 I am listening to real Hi-Res sound or whether airplay necessarily turns the music into CD quality.

I have read that apple tv reduces the resolution of Hi-Res tracks, but does the same happens with transferring the tracks directly from the Ipad to the airplay receiver of the NAD D7050?

By the way, Classics Online DD-LH seems to be a great streaming service for those who like classic music. Good classics selection (which it seems will grow in July with the addition of the Sony Music Catalog) and service that seems very reliable with great sound.