Looking at aplay, the only listed sound device is:
'card 0: rsnddai0ak4642h [rsnd-dai.0-ak4642-hifi], device 0: rsnd-dai.0-ak4642-hifi ak4642-hifi-0 '
Which I presume is the generic line-out on the board. I would expect HDMI to be a listed device but it seems not.
Is this known Stephen Lawrence ? I know for previous GDP iterations the use of external speakers has been recommended.
The pulseaudio user service which hooks into the am_poc.pa expects the master sink device to be 0,0 meaning that the AM Monitor does not fall over, as it did with the minnowboard as 0,0 exists.