I want to be able to record what my sound card outputs on the speakers / headphones. This question is all over the interwebs again and again, and there seem to be two outcomes:
in your selection of audio input devices, there's a device called "Stereo Mix", or similar, which is the "loopback" device for audio. Choose that in your recording tool and you're done.
there's no such device and only speculative posts about why that may be.
Now, I'm using ALSA and an Intel HDA chipset on my mainboard under Kubuntu Karmic. I have some 5-10 output channels and "Mic", "Front Mic" and "Line" for input. All of those are available in KMix, Audacity and other software. No "loopback" / "Mix" / whatever.
Do I have to
get some driver / kernel module
set up ALSA in some way
set up my system configuration in some way
use a software solution (such as JACK)
I had a look at JACK, and found it rather hard to understand, it's either an expert tool or just clumsy, I couldn't say. At least, I wasn't able to figure out how to achieve what I wanted.
One of my problems seems to be that I don't understand where and how the mixing happens. Are there sound cards which just aren't able to do it? Why does the sound card matter at all, since I could in theory grab the data stream at some point before it goes to the hardware, right?