Comment 13 for bug 1275198

( 0.087| 0.000) D: [pulseaudio] alsa-mixer.c: Probing path 'analog-output-speaker'
( 0.087| 0.000) D: [pulseaudio] alsa-mixer.c: Probe of element 'Hardware Master' succeeded (volume=0, switch=0, enumeration=0).
( 0.087| 0.000) D: [pulseaudio] alsa-mixer.c: Probe of element 'Master' succeeded (volume=1, switch=1, enumeration=0).
( 0.087| 0.000) D: [pulseaudio] alsa-mixer.c: Probe of element 'Master Mono' succeeded (volume=0, switch=0, enumeration=0).
( 0.088| 0.000) D: [pulseaudio] alsa-mixer.c: Probe of element 'Headphone' succeeded (volume=3, switch=1, enumeration=0).
( 0.088| 0.000) D: [pulseaudio] alsa-mixer.c: Probe of element 'Headphone2' succeeded (volume=0, switch=0, enumeration=0).
( 0.088| 0.000) D: [pulseaudio] alsa-mixer.c: Probe of element 'Speaker' succeeded (volume=0, switch=0, enumeration=0).
( 0.088| 0.000) D: [pulseaudio] alsa-mixer.c: Probe of element 'Desktop Speaker' failed.

since the volume control at node 0x13 is shared by dock line out and internal speaker

the pulseaudio speaker path does not contain pcm playback volume

http://cgit.freedesktop.org/pulseaudio/pulseaudio/tree/src/modules/alsa/mixer/paths/analog-output-speaker.conf

( 0.089| 0.000) D: [pulseaudio] alsa-mixer.c: Removing path 'analog-output' as it is a subset of 'analog-output-speaker'.

your case are similar to

https://bugs.freedesktop.org/show_bug.cgi?id=70865

line out and internal speaker share a volume control, pulseaudio don’t include pcm in speaker path