Hi guys, appreciate this is a bit derivative but I spent a fair bit of time googling how to set up a RaspyPlay 4 board with RuneAudio so thought I would share my build video here and possibly save others the trouble.
Main step is to open the config.txt file once you've flashed your SD card with RuneAudio (before you eject it from your PC). Then ctrl+f and type in IQaudio and hit find.
uncomment (remove the #) from the line "# dtoverlay=iqaudio-dacplus"
Then insert the SD card in the Pi, boot up and from Settings--> MPD menu select the audio output interface dropdown box and select IQaudioDAC!