Ah, this seems to be a quirk in the firmware handling/parsing of dt parameters - the dtoverlay scope of vc3-kms-v3d, which is loaded in distroconfig.txt on RPi2/3, seems to persist after the include in config.txt so the audio parameter applies to the overlay.
The solution is quite simple, clear the overlay scope with "dtoverlay=" or move the dtparam=audio=on statement up, before the include distroconfig.txt.
eg
Codedtoverlay= dtparam=audio=on audio_pwm_mode=1so long,
Hias
I have some hearing problems, I would very much appreciate if the latest version acts just like 9.2.6. so that it supports hdmi+analogue. My family gets to listen on the speakers and I get to listen at the same time on the headphones. This works perfectly. I tried the fixed suggested but does not work still crackles like crazy.