Comment 22 for bug 1033996

there are two ports for ac97 codecs (eg. ad1985) without headphone volume control

  analog-output;output-amplifier-on:

  analog-output;output-amplifier-off:

https://launchpadlibrarian.net/106662599/PulseList.txt

so this is clearly a bug which introduced by colin's patch which remove the analog output as it is a subset of headphone