When using an external soundcard and direct sound output (higher sound quality) just one player must have exclusive access to the soundcard. For this setting there are two possible options:
1.Install Shairtunes for Squeezebox Server (easy installation on Squeezebox Server tab in Max2Play). With this setting all Squeezebox Clients will have Airplay support, but can’t run synchronized. That means you may just play sound via Airplay at one device at a time.
2. Setup Shairport on each Max2Play device and use advanced Settings in Shairport to automatically disable the Squeezelite player on the device once a stream is played via Airplay. This setting has the advantage of a dedicated Airplay Player on each device, that can be sychronized with iTunes to a multiroom setup.
And please make sure that the Airplay service is running, and the Hifiberry Digi+ sound card is selected as default sound card, we recommend yout to have a look at Max2Play Raspberry Pi 2 Image for HiFiBerry Sound Cards DAC+ Amp+ Digi+
