Hello Greybeard
I know exactly what you mean. If sound appears from the speakers then that information had to pass thru the audio device and it should be simple to capture that data. It isn't that simple in practice but you should be able to get recordings of what you want. First let's try to fix that error situation.
Since you're using KDE a good place to start is in KDE System Settings > Multimedia > Phonon (and yes there are ways to do essentially this through CLI but seeing it can provide some insight and there's no penalty in this case to the GUI).
On the Device Preference tab there is a list of what devices the system has found and a test button below so you can determine what works best, least, or not at all. Set that up to your liking or confirm that it is already optimal. Then on the "Backend" tab it is my understanding that "GStreamer" is best. Since I have MPlayer and Xine setup I find no problems with those but apparently GStreamer may be better in some situations so I choose that as advised since in every other way I detect no difference.
This should likely solve error problems and give a known good place to start. Then you can try an app meant for recording like Audacity so you have the benefit of setup choices and verbose error logging to get to the heart of any issues that may remain. Once you know you can record at all, then try your CLI work ie arecord.
Since you seem used to some old OSS conventions a look around alsa-project.org maybe starting with
http://www.alsa-project.org/main/ind...x:Vendor-Intel may be helpful. You may need to create an .asoundrc file for direct recording. The site will have examples as well as explanations.
