Comment 33 for bug 280534

Same thing for me on XPS 1330.

When using alsa only (disabling pulseaudio) the mic works fine (after selecting digital input source = digital mic 1 and maxing the "digital" recording level). With pulseaudio recording works but volume is too low.

Something interesting I noticed is that, when recording through pulseaudio, the volume is not affected by the "digital" level in alsamixer. You can turn digital to 0 and still record with the same (low) volume. I find this strange (for example lowering the master playback level in alsamixer lowers the volume also in pulseaudio). Maybe pulseaudio gets it's input from somewhere else and not from digital? (I'm not an alsa/pulseaudio expert though so I might be missing something)