The given task was in this case: record the output of a flash streaming online radio. In principle this shouldn’t be difficult because the data are on your computer - you just have to route them through a recording tool.
However, this is the point which is a bit odd: how do you route sound? And, also difficult at least on KDE, which recording tool can you use? I never really

understood krec, so that was out of question. Also, it seems to require artsd, which infers with the flash plugin which uses Alsa.

The first solution I found didn’t work out: the man page of asound gives code snippets to do this task. However, it didn’t work for me, and the net was only full with people where it didn’t work either, so no chance there.

HowTo