Hi hawkesley,
hawkesley wrote...Is it possible to access the cml from the UI...
No.
hawkesley wrote...I want to enable the HiFi berry AMP+ from the /boot/config.txt file...
If you are using RuneAudio v0.5b you can configure config.txt automatically via the UI.
In the Settings UI select 'HiFiBerry Amp' in the 'I²S kernel modules' pull down menu, then reboot. You should then see it as an audio output in the MPD UI.
janui