yeah looks like pulseaudio will work for me, it is runnable headless and also includes a ducking module which is useful.
I can confirm installing pulse audio and in /etc/pulse/default.pa commenting out the module
load-module module-suspend-on-idle
cures the click on speaker hat, but pulse audio sits using 1-2% cpu on a pi zero when idle
aplay works OK however cant figure out why the following command does not work
pacmd play-file test.wav 0
no error, just does not play the file.