Package: installation-guide
Version: 20150528
en/hardware/supported/arm.xml says:
[..] Support for
the onboard audio options (analog, S/PDIF, HDMI-Audio) and for
the onboard WLAN/Bluetooth module is not available in &debian;
8.
I don't know if this is true or not but in the case the Debian 9 install
guide shouldn't refer to Debian 8.
--
Martin Michlmayr
http://www.cyrius.com/