When I am on conference talk and others don't hear me well it is not blatantly obvious in KDE what mic is being used (built-in mic or headset mic) and if I should get closer to the laptop or adjust microphone at the headset.

Several situations demand better user control (in addition to the automation), it is about security and confidentiality:

Consider for now only built-in laptop microphone and combo audio jack (microphone, speaker). Ignore for now bluetooth and usb microphones/headsets. Some laptops have a way to notify kernel if audio jack is plugged. 

1) Sometimes laptops kernel do not detect (due to hardware limitation or bug in kernel) the plugged standard 3.5 mm combo audio jack (in/out headphone/microphone) ,
so the OS cannot switch the default audio out/in source/sink.

2) sometimes audio combo jack headset/microphone is bad, weak or buggy and user wants to make sure or test he/she is talking to the active microphone in the headset and wants to disable built-in microphone

3) user wants to have a confidence he/she is not being spied on or she does not want to make an easy mistake due to confusing user interface (many marriages have been broken by disclosing  the secrets by mistake). User can easily unplug headset to make sure microphone is NOT being used. However the user cannot easily unplug (without hardware kill switch) the built-in microphone. The user has never the confidence the built-in laptop microphone is not being used possibly due to software bug or virus, confusion or mistake. Especially if there is an automatic switching source mechanism in place when audio jack is plugged in the confusion and doubt can creep in what source is being used.


All those situations could be  handled if both audio sources/microphones (built-in one and combo audio jack mic) are available in the system tray audio volume all the time (and especially if the audio jack is plugged) and what is switched (if possible) is only the default audio source/mic. Also volume meter with mute and mic boost checkbox for each mic in audio volume applet/widget (including bluetooth and usb mics) would be great too. To avoid confusion the checkbox mute must be next to the explicitly stated location: Built-in/internal microphone  at all times, and another checkbox next to the "audio jack" microphone/headset (when plugged in) at least when the headset/microphone is plugged in (if possible to detect). I would avoid displaying name such as "Digital microphone" in audio volume applet/widget. (as it is doing now to me).What matters to me is where the mic is , not what type it is. The name "External" is not good as well as there can be multiple bluetooth or usb microphones/headsets, but the 'audio jack' headset is just one.
+35dB boost checkbox next to those microphones would be great next to the volume meter for each mic (including usb and bluetooth mics).
Some feature can be put in systemsettings/pulse/audio


Linux/KDE Plasma: 
(available in About System)
KDE Plasma Version: 5.21.4-0ubuntu1
KDE Frameworks Version: plasma-framework 5.80.0-0ubuntu1 
Qt Version: 5.15.2+dfsg-5