external analog microphone volume is clipped at 50%
the amixer settings we do for the external mic are https://source.puri.sm/Librem5/librem5-base/-/blob/pureos/byzantium/default/audio/ucm2/simple-card/HiFi.conf#L151
In g-c-c audio settings one can already see that no matter how loud the signal should be (by tapping onto the mic itself for example) the recorded signal never exceedss 50% of the scale.
Not yet sure whether it's a kernel or config bug.
After this is fixed we can think about bumping the gain another 3 or 6 dB in case it's too quiet still.